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Garden Pests - InsectsAnts on willow tree
Aphids on Arizona ash
Aphids on globe willows
Aphids on Spanish Broom
Bark beetles
Bark beetles from woodpile
Bees – are they killer bees?
Beet leafhopper, curly top virus outlook
Black dots on leaves
Borers in Ash
Box elder bugs
Cochineal scale on prickly pears
Eggs look like melon seeds
Elm leaf beetles
Fire Ants in NM
Firewood has insects, dust
Fungus gnats
Grasshoppers eat anything?
Grasshoppers, eliminating
Grubs cause dead grass patches
Grubs: How and when to kill them
Grubs in compost
Insect update: cold winters help
Insects appear on houseplants in winter
Japanese beetle invasion
Japanese beetles - a NM threat
Juniper insects killing twigs
Pine tip moth control
Pine tip moth, spraying
Pinon sawfly
Piñon tree borers
Pitch moth control
Roaches killed with boric acid?
Spider mites
Spiders on pine tree
Scale problem on fig
Scale insects on ficus
Thrips on irises
Wasps, eliminating
Web worms
Whitefly control
Ants on willow tree
Q. I have three Weeping Willows in my yard that are about four years old. One of them has red & black ants on it. Are they a problem? Don M. via internet
A. The ants are probably not a major problem, but an indication of other problems. While it is possible that the ants are carpenter ants which can mine dead wood in the tree, it is more likely that the ants are present because there are aphids in the tree. Aphids feed on the sap of the tree and can spread plant diseases. They are likely to be the real problem. Do you see a silvery sheen on some of the leaves? This is the honey dew excreted by the aphids. This is also the sugary substance which is attractive to the ants. Aphids can often be washed from small trees and shrubs with a strong jet of water from the garden hose. Of course, they will climb back into the tree or shrub, but while climbing they will not be harming the tree. However, even while they are climbing into the tree after being washed out, they are prey for many types of predatory insects. You can use a pesticide, but this will harm the beneficial insects that prey on the aphids. This is a good time to avoid the chemicals if possible.
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Aphids on globe willows 4-02
Q. My three large globe willow trees were infested with tiny black bugs last year. These bugs were very tender and, if touched, left a reddish-colored spot. I was told that they were aphids. They covered the trees until the limbs were black with insects and a sticky sap covered the stems, leaves, and grass beneath the trees. In the late afternoon, they would be crawling on the concrete patio. I tried using a lot of different insecticides to get rid of them; it almost seemed that they were being nourished by these chemicals. I dread going through another summer with them. What can I do?
A. Your identification is correct. Aphids are soft-bodied insects that will infest globe willow trees and many other plants. The produce the syrupy "honeydew" you described, and they can be hard to control.
If you choose to use insecticides, you will need to make applications every few days to "clean up" any insects you missed. Even a few surviving insects will rapidly reproduce and repopulate the tree with aphids. After three to five applications of insecticides, wait a while to see if the aphids reappear. Be sure to read and follow the directions on the insecticide label.
As you have already observed, insecticides sometimes fail to totally eliminate the pests. There is an alternative to the insecticides that you can try. This non-chemical approach will also not totally eliminate the pests but may reduce their numbers sufficiently to make them a non-nuisance. In this alternative treatment you will use strong jets of water and, if necessary, insecticidal soap. Use the soaps carefully because they can injure the leaves on your tree. By washing the insects from the tree frequently (blasting them out with strong jets of water from the garden hose), you will disrupt their feeding and reduce the production of the sticky honeydew. Not using insecticides will allow the development of populations of predatory insects that make their "living" by eating aphids and other garden pests. We want to encourage these beneficial insects and not poison them with insecticides. Beneficial insects include ladybird beetles, syrphid flies, parasitoid wasps, lacewings, and others. There are many things that eat aphids; that’s why aphids reproduce so rapidly.
Aphids also have "friends" in the insect world. Ants like to feed on the honeydew, so they often "herd" and protect aphids. To prevent the ants from interfering with the beneficial insects that eat aphids, you can put a band of sticky substance around the base of your trees. This may be a strip of old-fashioned fly-paper or other sticky material to keep the ants from climbing the tree to protect the aphids. The ants will become trapped in the sticky trap. After enough dead ants or dust and debris covers the sticky material, you will need to replace or renew the sticky surface. Use of non-insecticidal methods of controlling aphids is often more effective because there are so many insects that feed on aphids. In addition, some of these "aphid eaters" are also pollinators for herbs, flowers, and vegetables. So, the good-guys are doubly good. Take care of the beneficials and they will take care of your aphid problem.
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Q. I recently removed a globe willow tree in our yard that was infested with aphids. Following the recommendation of a nursery, I applied an insecticide several times over the past 2 months. It did not work, and the tree continued dying branch by branch. The stump has been removed, and I was planning on leaving the area fallow until spring. I will plant another tree at that time, possible a peach. Is there anything that I should use to treat the soil before replanting in the same hole?
A. Based on what you have written above, I think there is nothing to worry about if you replant at the same site without treating the soil. It is wise to plant something besides a globe willow at that site in the unlikely event that there was a disease involved. The aphids may have weakened the tree but are probably not the ultimate cause of tree death.
The globe willow tree is subject to many problems other than aphids, which are common on globe willow. There are borers that may attack and cause gradual branch dieback, and the drought makes it difficult to provide enough water to the willow. Lack of sufficient water can cause branch dieback.
Neither borers nor drought create a residual problem in the soil. Drought is, of course, related to soil moisture, but proper irrigation remedies that problem.
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Aphids on my spanish broom 7-99
Q. I noticed aphids early this spring attacking my Spanish Brooms. I bought a spray recommended by a nursery, but this did not work. I ended up just hosing down the aphids when I water my lawn. This seemed to help although it did not completely solve the problem. At least the bushes are flowering although not as abundantly as last year. Any suggestions?
A. You did well. I am surprised that a spray labeled for control of aphids did not work well because aphids are not especially hard to kill. However, I agree with your use of strong streams of water to just wash the aphids off the stems. You will not get all of them in that manner, but you should reduce the number of aphids to a level that causes little damage. They will try to climb back onto the plants, but you can keep washing them off. When you don’t use insecticides, you maintain an environment which allows beneficial insects to increase. There are several "good" bugs that eat aphids and in time they will appear and eat the aphids, keeping the aphid population low enough to limit their damage. This will reduce the need for you to be out washing the aphids off. If you use insecticides, you can kill the aphids, but you will also kill the lady bugs, lace wings, syrphid flies, and other aphid predators.
Pesticides which kill the lady bugs result in the return of aphids later without opposition from the predators. This "resurgence of pests" occurs much more rapidly than the resurgence of the predators, so it becomes necessary for you to continue to intervene with streams of pesticides or water to keep the aphids under control. Whenever possible, use of low impact pest control methods helps to preserve the predators and reduce the need for constant intervention on your part. When there is a need for pesticides, organic or synthetic, be sure to read, understand, and follow the directions on the label.
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Bark Beetles
Q. A man stopped at my house yesterday. He said he was inspecting trees in my neighborhood and that my pine trees have bark beetles. For a fee, he will treat my trees by trenching around them and drenching with insecticide. Is this really necessary? My trees look good. A Master Gardener told me that my trees don't have symptoms of bark beetles and that treatment would not be necessary. Who can I believe?
A. You didn't say who it was that inspected your trees. Was this a licensed pesticide applicator - or just a guy wanting your money? Based on your description of the health of your tree and the absence of symptoms and signs of bark beetle, I fear that this is not a reputable pest control professional that has "inspected" your trees. If bark beetles have infested your trees, it is too late to treat the infested trees. The beetles do their damage so fast that by the time you recognize that the trees are infested, treatment will not save the them. Your only option in this case is to treat nearby uninfested trees to prevent the beetles from attacking them. According to Bob Cain, NMSU Extension Forest Entomologist, the treatment recommended would not be effective even if there was time to save the tree. Systemic insecticides absorbed by the roots will not affect the bark beetles which feed on the phloem. Chemicals absorbed by the roots do not readily enter the phloem and would therefore not control the bark beetles. All of this, along with the absence of bark beetle signs, sawdust on the bark and branches, the absence of pitch tubes, and the apparent health suggest that the Master Gardener gave you excellent advice. It is wise, however, to get another opinion from a neutral party when you are faced with conflicting recommendations.
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Bark beetles from woodpile
Q. A friend told me that my trees can get bark beetles from firewood. Is that true? Will they hurt my landscape trees?
A. It is possible to import problems into your landscape if the firewood was cut recently. In addition to bark beetles, there may be other insects to consider. Most are of little concern except as a nuisance if they exit while the firewood is in your home. However, the bark beetle and the twig beetle may cause problems for other pine trees in your landscape.
Store the firewood in a sunny location as far away from your pine trees as possible. Cover this firewood with clear plastic and seal the edges of the plastic to the ground with rocks or soil. The clear plastic will confine the beetles, limiting their opportunities to infest surrounding trees. In the sunlight, the clear plastic will capture heat like a greenhouse. This heat can kill the larvae and beetles remaining in the firewood.
Trees other than pines, especially deciduous trees, are unlikely to be infested by these bark beetles and twig beetles, but it is a good practice to store the firewood under plastic anyway. This will keep it dry and protect neighbors’ trees.
There may also be borers that attacked the firewood after the bark beetles and twig beetles. The borers are less likely to kill your landscape trees but can cause some problems. A greater concern to you will be emergence of these borers inside your house if you store firewood indoors. Bring the firewood indoors as needed, rather than storing it indoors for extended periods of time.
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Black dots on house plants’ leaves 12-01
Q. I have little black dots on the underside of some of my house plants, including the stalks. What could this be and how do I treat it?
A. Are the dots moving? Are they easily smashed? Do they rub off easily? Is there a sticky substance around the drops or on the leaves and stems below? You may be observing insects on your house plants. If they rub off easily and are easily smashed, they may be aphids. These may be washed off the plant by placing them in the sink or bath tub and washing the plants with a strong stream of water. You will need to repeat the process periodically. You can also use insecticidal soap (a safe insecticide for indoor use). Put the plants in the sink or place an old sheet or a plastic sheet under and behind the plant so that the spray will not damage carpet, upholstery, or draperies. If you wish to use other, stronger insecticides, wait for a period of warm days when you can apply the insecticide outside and leave the plants there until the product has dried and there are no objectionable odors.
If the spots don’t rub off or smash, you may have scale insects which are more difficult to treat. However, these may be treated with horticultural oil (more likely to stain fabrics in the house than the insecticidal soaps). Before treating the plants, be certain that the spots are not natural pigmentation. Some plants will produce such spots naturally. When using chemicals for pest management, be sure to read, understand, and follow the directions on the pesticide container.
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Black specks and damage on pinon pine 2-00
Q. I have a pine tree in my yard. It’s thinning - that is, there aren’t a lot of needles left on it. The green needles that are left have black spots on the underside of the needles. Are these bugs? Is it killing the tree? Will this tree survive? What to do, oh my? It gets mostly morning and early afternoon sun. We just moved into the house 3 months ago from the east coast. Should I be watering the tree? Would that help?
A. You have described pinyon needle scale, an insect that attacks pinyon pine trees. The scale insects are debilitating for the tree but not immediately fatal. It is important to manage the problem to maintain the health of the tree.
The black spots on the needles are the waxy covering that the insect builds over itself. This covering makes chemical control difficult. According to Bob Cain, NMSU Extension Forest Entomologist, the scale insects feed by sucking the sap from the leaves. Normally, pine needles persist for several years before falling from the tree. Needles infested by pinyon needle scale turn yellow in the spring and fall earlier than they should. By reducing the number of needles remaining on the tree, the scale insects cause the thin appearance of the tree. This also reduces the number of needles producing food for the tree. According to Bob Cain, heavy infestations of pinyon needle scale can kill small trees and weaken larger trees, predisposing them to attack by other insects which may then kill the trees.
Cain explains that adult, wingless female scale insects emerge from their scale covering in mid-to-late April to mate with winged males. The females lay their yellow eggs in clusters held together by white, cottony webbing around the root collar of the trees, on the undersides of large branches, in branch crotches, or in cracks of rough bark. Sometimes the eggs are found several feet from the base of the tree on rocks or logs. It is at this time that the scale is most vulnerable to control measures. In the 5 weeks until the eggs hatch, the eggs in their cottony webbing may be removed from the tree by a broom or strong jet of water. This material with eggs may then be disposed of, removing the potential for reinfestation of the tree by the next generation of scale insects.
Cain further states that there is still a brief period during which insecticides may be effective if the egg masses are not removed before hatching. Once the eggs hatch, the scale nymphs, called crawlers, climb to the ends of branches and settle on the previous year's new growth. They insert tube-like mouth parts into the needle and cover themselves with the protective wax covering which then turns black. While the nymphs are crawling into position on the needles and until the wax is produced, the insects are exposed to chemical control.
To determine if the scale crawler nymphs are still exposed, hold a sheet of dark construction paper under the needles and. with a gloved hand, sharply strike the branch above the construction paper. Look for small insects crawling on the paper. If the nymphs are found still exposed, application of a properly labeled insecticide will help reduce the level of infestation and the damage to the tree. Repeated applications at 7 to 10 day intervals may be needed as additional eggs hatch and new crawlers move up the tree. Always remember to read and follow the label directions when using any pesticide.
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Borers in Ash Tree 9-00
Q. The leaves on my ash tree have turned a yellow-green color. I consulted with a person at a nursery who informed me that I probably have borers. There are several holes in the tree, and I am afraid that this tree will be lost. Several other ash trees in our neighborhood have been destroyed by some type of infestation. The nurseryman suggested a Dursban® based product. Will this take care of the problem? In addition, the tree seems to be slanting more than I remembered last season. Does this have anything to do with the borers?
A. Borers and ash bark beetles are candidates for the source of the problem you have described, but there are other factors to consider as well. The holes in the trees may be due to these pests, but they may also be due to other factors.
The ash borers tend to attack the trunk and, sometimes, the larger branches. After the larvae have finished feeding, they pupate and emerge from the tree, leaving holes in the trunk. They tend to leave their pupal cases extending outward from the tree at the point from which the adult moths emerged. These pupal cases are tan or brownish and papery. This occurs in late summer and is characteristic of the borers. Have you observed these pupal cases remaining on the tree trunk?
The ash bark beetle is most commonly seen in the twigs, though they may move into the larger branches once the tree is heavily infested. Evidence for the bark beetle is small, pin-head sized holes in the twigs. It is often possible to very easily snap the twigs at points where the bark beetle, or other small beetle, has girdled the twig by eating the cambium layer just below the epidermis layer of the twig.
The insecticides mentioned below, and others labeled for use on ornamental or shade trees, can be effective in limiting the damage caused by these insects. It is important to apply chemicals at the time when they will be effective. Check with your County Extension Agent for the proper time of year to apply these products once you have determined whether it is borers or bark beetles doing the damage. Whether or not the pesticides will be effective also depends on the extent of the damage which has already occurred.
As I said, there are other factors which could also cause these problems. Accidents with or misapplication of lawn weed control chemicals could cause these problem. A very common problem that may cause the symptoms you described is the "southwest injury" so common on young trees in New Mexico. This is damage to the bark caused by alternate freezing and thawing of the bark on these trees in the late winter. In this case, the sun warms the south and southwest side of the tree, thawing the bark each day. The bark then refreezes at night. Repeated freezing and thawing can damage the bark. This damage is revealed later in the year by patches of dead and flaking or peeling bark on the southwest or south side of the tree.
If this is the case, there may be borers exploiting the damage, but the real problem is the freeze/thaw damage. To prevent such injury next year, paint the trunk of the tree or other areas that are exposed at a direct angle to sunlight, with white water-based paint in late fall. This reflects the sunlight, reducing the winter heating of the bark. Use of insecticides would not be beneficial in this case unless there is evidence of insects exploiting this injured area. If the area of the tree trunk injured by southwest injury is extensive, the tree may be slow to resume normal growth or may never recover.
The leaning is probably not directly associated with the other problems. It may be the result of poor root development on one side of the tree or due to our winds.
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Box Elder Bugs
Q: We are having difficulty eradicating box elder bugs. Do you have any suggestions. Would getting rid of the tree solve the situation?
A: The box elder bugs and their close relatives, the red-shouldered bugs, are true bugs in the order Hemiptera. They are black bugs with red or orange markings on their shoulders and along the edges and ends of their wings. They feed on the box elder and golden rain tree seeds causing little damage to the trees. They are numerous and have a bad habit of invading homes, making a nuisance of themselves. This is the reason most people seek to control them. Removing the tree can help solve the problem if there are no other host trees nearby. If there are other box elder or golden rain trees in neighboring landscapes, you will continue to have the bugs, but they should be fewer in number. If yours is the only host tree in the neighborhood, your neighbors might appreciate anything you do to eliminate the bugs. There are several pesticides which may be used. Insecticides containing chlorpyrifos (TM) are often used for this purpose, but there are others also labeled for control of box elder bugs and their relatives. These insecticides are much more effective at eliminating very young bugs; the older bugs often hide inside the seed clusters of box elder or in the "Chinese lanterns" around the seeds of the golden rain tree. In these hiding places, they are exposed to less insecticide and as larger insects, they are less sensitive to the insecticides.
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Cochineal scale on prickly pears 9-02
Q. I want to rid my prickly pears of cochineal scale. I’ve heard about blasting them with water, and using an alcohol or soap solution. Is there anything more I can try? The water spraying helped, but can’t that go too far with a cactus?
A. The cochineal scale, source of a natural red dye, can be damaging to the cacti if they build to large numbers. Blasting with water will help keep the population low as will manual removal with swabs treated with rubbing alcohol. Insecticidal soap can also be used. Insecticidal soap, manufactured and labeled for pest control, is better to use than other types of soap. If all else fails, there are insecticides labeled for controlling scale insects.
This scale insect can kill whole prickly pear plants, but that takes a long time. Using water or insecticidal soaps on a frequent basis may be sufficient to prevent significant damage to the prickly pear cacti. In time, natural predators should arrive to help with the control of the scale. In considering your questions and the treatments mentioned, it appears you prefer not to use the more environmentally impacting insecticides. They are an option if all else fails. If you use the commercial insecticides, remember that you may also eliminate these beneficial predators.
Regardless of the method you choose, if you use soaps, oils or the other insecticides, use them carefully and according to the label directions.
You also wondered if blasting with water could be damaging to the cacti. Prickly pear cacti are fairly tough, so they may tolerate the extra water if you do not treat too frequently. Treatment once a week for a few weeks should do little damage if the soil is well drained. If you use a low volume, high-pressure spray, you can control the insect without applying a lot of water. The objective is to keep the pest population low enough for the plant to tolerate until beneficial insects arrive to help.
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Elm leaf beetles
Q. A few weeks ago you wrote about elm leaf beetles and said that they did not hurt the trees. Here in Ft. Sumner they are eating all the leaves from our trees. Doesn't that hurt the trees? Shouldn't I do something?
A. In most years the elm leaf beetle does damage which is more cosmetic than damaging to the long term health of the elms. That is because the beetle population is sufficient to cause considerable damage, but not enough to cause defoliation sufficient to permanently harm reasonably healthy trees. This year, in some parts of New Mexico, the elm leaf beetle populations are considerably greater than typical. Damage is more severe than usual and the health of the tree and type of elm are factors which must be considered. Our common Siberian elms have proven themselves capable of tolerating considerable stress from the environment, insects, and diseases. Other elms, especially the American and English elms, are less weedy and are more likely to be damaged. Elms such as the lacebark and cedar elms have tougher leaves which are usually less damaged by the beetles.
The article you recall is one in which elm leaf beetles were causing a problem in a home. In that case pesticide treatment was not warranted. The trees were not as severely affected as you describe in your situation. The question is whether or not you should spray. If your trees are Siberian elm, often called Chinese elm in New Mexico, and have been reasonably healthy and growing vigorously, you may choose not to spray. Even if the trees are totally defoliated, healthy trees will resume growth next year. If the trees are old and declining, severely infected with diseases, or had been damaged by previous winters' cold and summers' drought, you may choose to spray. If next winter is unusually severe, even healthy trees may suffer damage following complete defoliation by the beetles. Since the adult beetles can fly, your trees may be reinfested even though your treatment killed most of the larvae on your trees. Several applications may be necessary. However, we are nearing the end of their reproductive phase for this year, so treatment this year may provide little benefit.
If you choose to apply pesticides, you have several options. There are several insecticides labeled for use on ornamental trees to control leaf beetles. Many homeowners apply carbaryl insecticide though some prefer to use the San Diego strain of Bacillus thuringiensis (B.t. San Diego) which is specific for control of beetle larvae and has little other effect on the environment. Carbaryl is available in most places where you can buy garden chemicals. The B.t. San Diego may be more difficult to find; you may have to order from a mail-order supplier. Because you have so many elm leaf beetles in the area, expect them to invade your home in the late summer and fall as they look for places to overwinter. To reduce the nuisance problems from these insects indoors, make sure weatherstripping around doors and windows is in good condition and seal or cover with screen door material all holes into the house, attic, or crawl space.
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Fire ants in New Mexico
Q. I moved from Texas where fire ants are a problem. I have heard rumors that the fire ants are in New Mexico as well. Is that true?
A. According to Dr. Carol Sutherland, NMSU Extension Service Entomologist, red imported fire ants were collected and identified in 1998 with samples from a residence in Las Cruces. So, yes, they are now in New Mexico. The have subsequently been found in Dona Ana county in residential areas from the northern part of the county to the Texas border. You are familiar with the problems associated with fire ants, but others who have not experienced them before may find the following information from a news release by Dr. Sutherland interesting.
Dr. Sutherland warns that fire ants can attack in force, many crawling on a victim, often unnoticed, then many begin to sting at the same instant. Each sting produces nickel-sized welts, each with a pustule. These are painful as well as intensely itchy and were slow to heal. This in itself is not proof of fire ants, but suggests that the possibility should be considered by sending a sample to the New Mexico Department of Agriculture. Dr. Sutherland said that samples containing a large number of the ants should be taken to your local Cooperative Extension Service office so that they may forward them to the New Mexico Department of Agriculture. For more information about fire ants in New Mexico, it is available on the NMSU website at <http://www.cahe.nmsu.edu/>.
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Firewood has insects, dust
Q. I was stacking pinon firewood the other day and noticed a lot of sawdust and small insects. Is this something to be concerned about?
A. The sawdust may indicate the presence of pine bark beetles. It may also indicate borers. The insects you saw may or may not indicate a problem because there are many insects that will inhabit firewood piles. Many of the insects in the firewood are benign. The bark beetles are the greatest concern. If you peel the bark from the wood and find engravings, the tunneling patterns left by bark beetles as they feed on the layer just under the bark, you have a concern. Borers will also leave engraving marks, but they are usually broader tunnels. You may also find the adults of these insects. Your County Extension Agent can help you identify what insects you have found and if they will be a problem.
To be safe, stack firewood away from pine trees in a sunny location. Cover the firewood with clear plastic and seal the edges with soil if the firewood is showing signs of recent insect activity (fresh sawdust). This covering with clear plastic in a sunny location will allow the heat from sunlight to kill the beetles, and it will also contain the beetles keeping them from infesting your nearby landscape trees.
Covering the firewood with plastic will interfere with the curing of the firewood, so after a month or two uncover the firewood to allow it to cure before burning. Cured firewood may have borers but will not have active bark beetles and will not need to be covered. When possible buy aged, cured firewood.
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Fungus gnats 9-03
Q. I am repotting plants to bring indoors in the autumn. Last year I had problems with fungus gnats. Is there a way to avoid this problem?
A. The fungus gnats may be present in the potting soil you are using, so careful choice of potting soil may help solve the problem. Pasteurization of the potting soil before use by heating to a temperature of 160 degrees F. can also help.
If you find that you have fungus gnats once you bring the plants indoors, there are some organic pesticides based on the Bacillus thuringiensis toxin that can be used safely indoors. There are other products available for use on potted plants. Read and follow the label directions to maximize effectiveness and safety (for you and your plants). If instructions do not tell you it is safe to use indoors, you should take the plants outdoors to treat them and bring them inside after the chemical has dried.
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More about fungus gnats 8-02
Q. Every year I seem to get gnats in my houseplants and they are driving me crazy. I have tried many "recipes" to get rid of them but to no avail. Do you have suggestions?
A. You probably have fungus gnats inhabiting the soil of your potted plants. The larvae may feed on the roots of potted plants, stunting the growth of the plants. It is the adult gnat that you are probably seeing. These small insects are a nuisance but do not do as much damage as their larvae.
Cultural practices that reduce the population of fungus gnats include letting the surface soil of potted plants dry between waterings and repotting in a well-drained potting soil that does not stay moist for a long period of time. Potting soils should be pasteurized (treated to kill detrimental insects, diseases, and weed seeds). These practices reduce the population of the larvae in the soil.
To reduce the number of adult fungus gnats in the home, you can use "yellow sticky traps". The gnats are attracted to the yellow color and become stuck in the sticky material removing them as nuisances from the home environment.
A natural toxin produced by Bacillus thuringiensis subsp. israeliensis is effective in controlling fungus gnats. It is sold under the name Gnatrol®. This product may be used to drench the soil, killing many of the larvae.
A combination of treatments will probably be most successful. When you use a chemical means of controlling fungus gnats, it is important to read, understand, and follow the label directions.
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Grasshoppers eat anything? 8-02
Q. I have always wondered about the grasshoppers that attack my garden most years. Is there anything I can plant that they won’t eat?
A. Dr. Carol Sutherland, NMSU Extension Entomologist, told me that there is a grasshopper to eat any plant you may grow. Not all grasshoppers eat all plants; some are very specific while others are not picky eaters at all.
She says that there are at least 160 described species (implying that there may be even others yet to be discovered and described) in New Mexico. A couple of these prefer to eat weeds and could be considered beneficial. Of the remainder, about 40 species have the potential to become major pests. Some of these prefer grasses, others broadleaf plants, and some both. The extent of the problems we have in our landscapes depends on which species are present (usually more than one), how many of them are present, and what they prefer to eat. I find the following statement from Dr. Sutherland very informative. "Short of rebar, steel, aluminum, adobe, rock, asphalt, and concrete, I can’t think of many substances that will be little damaged consistently by grasshoppers of one kind or another." So, in one year we may have less problems; in another year, we may have more problems.
Dr. Sutherland also explains that the weather affects the numbers of grasshoppers. Drought, especially in the early spring, can greatly reduce the grasshopper population, and thus, the damage done by grasshoppers. When we irrigate, we help the grasshoppers avoid the spring drought dilemma. Careful and limited irrigation of landscapes may help, but the river valleys are also escape valves for grasshoppers. If they can make it to the valleys, they will survive and be able to migrate to our gardens.
There are chemicals to use, but their effect is limited by the fact that grasshoppers are migratory. Adult grasshoppers have wings and can fly into our gardens. So, after we kill some, new grasshoppers arrive to continue eating our garden plants. Some people prefer the insect diseases that may be purchased as biological control for grasshoppers. These are effective with some species but not all species. Some gardeners claim great success using guinea fowl, turkeys, and other birds that eat grasshoppers. Unfortunately, the birds (biological grasshopper control agents) also eat garden plants.
Grasshoppers are a difficult problem for gardeners in our area. For the very adventurous gardeners, Dr. Sutherland states that grasshoppers are edible and highly nutritious. I think that is good information for the guinea fowl (I am not yet ready to eat grasshoppers).
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Grubs cause dead grass patches
Q. I have found patches of dead grass. When digging at the edges of these areas of dead grass I found large white worms with brown heads. What are they and what should I do about them?
A. You have described white grubs. These are the larvae of the May beetle or June beetle. These are the light brown to honey colored beetles which fly around porch lights, street lamps, and other lights in late May and June. They also tend to make noise as they run into window screens when attracted to windows lit by interior lamps. You described their larvae and if you remember the beetles flying around last summer, that is extra confirmation that grubs are likely the problem. However, even if you don’t remember them, you probably have white grub problems based on your description. You can take a sample to your local NMSU Cooperative Extension Service office to confirm that you have collected grubs.
Another confirmation is the symptom you described, patches of dead grass. While other things can cause this symptom, the presence of the grubs at the edge, where the living and dead grass meet, makes it likely that grubs are responsible. Grubs eat the roots of the grass, causing the grass to die. With the roots removed, the grass can often be lifted from the soil like a rug. So, what should you do? At this time of the year you should do nothing.
The grubs are full grown and are not feeding much. They will soon pupate and begin the metamorphosis into June beetles. Because of their size and late pupal stage (just before pupation) they cannot be easily killed by pesticides. Besides, the damage that this generation will do has already been done. Yes, dead patches of grass are becoming apparent, but that is due to grub feeding when the grubs were smaller and more actively feeding. It is only just now appearing as the grass greens in the spring and as rising temperatures create and increased need for water which cannot be supplied by the limited root system left by the grubs.
In May and June the beetles will emerge from the soil, mate, and lay eggs. These eggs will hatch in late July and August. Once the eggs have hatched, you can treat with any of several insecticides labeled for use in managing lawn white grub problems. There is even a product which has a long residual duration in the soil so that its label recommends that you apply it in June, before the eggs hatch. However, most products should not be applied until mid-August (early August in the southern part of New Mexico). Contact your Cooperative Extension Service agent to determine which product you wish to use. Read the label on this and any pesticide before purchasing it to be sure it will do what you want and can be used in the type of grass, or other plants, you wish to use it. Be sure to follow the directions on the label carefully to maximize the benefits of the product.
If you wish to avoid the use of chemicals, there is a biological control method which employs parasitic nematodes, small worms which kill grubs. These can be mail ordered or in some cases purchased at local garden centers. Read and follow directions for the use of nematodes if you choose to use them.
The white grub so commonly written about in garden books and publications for the Mid-West and East are the larvae of the Japanese beetle. This is currently not a problem in New Mexico. Some products which are recommended for control of the Japanese beetle white grub, are not very effective in controlling the grubs common in New Mexico, so choose only products which are for white grub/June beetle control.
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How and when to kill grubs
Q. In the last two years, the pesky grubs have all but ruined my showcase 3-in-1 fescue lawn. One turf expert and reputable friend suggested that I start the following treatment in March: Diazinon or Dursban once a month for 4 months, Milky spore once a month for 4 months, and Oftanol once a month for 4 months. He tells me that all this will take effect in two years. Actually, I don't want to kill the whole world - I just want to kill these darn worms. What is your opinion? I recall a release you wrote not too long ago. It recommended starting treatment in June. Isn't this a little too late? As I recall, by June my lawn was turning rather yellow and on its way to disaster. At first, I kept adding water (flood irrigating) and ammonia trying to save my lawn, until I dug on the circumference as you suggested and found these creepy-looking things. The lawn returned to normal, of course, as weather cooled off.
A. I think the advice you have is overkill and improperly timed.
The June beetles lay their eggs in June and the eggs hatch into small (easily killed) larvae in August. By late autumn, the grubs have become larger and more difficult to kill. Their feeding damage occurs in the fall and a little in the early spring. The effect of the fall and spring damage becomes apparent in May or June. Treating in the spring may or may not kill them, but it won't prevent the appearance of damage already done. In the spring, after feeding only a little, the grubs burrow into the soil and form pupae. At this time, pesticides will have no impact on them. (It may damage other things.)
The proper time to treat depends on the product used. Imidacloprid (the active ingredient in several insecticide products) is safer to use than many other products. (It is still toxic, has a three month residual, and will kill the young grubs.) It should be applied in late June so that it is present when the eggs hatch and the larvae start feeding. Other products such as Oftanol® must be applied in early- to-mid August as the eggs are hatching. It is a good idea to monitor the effectiveness of your treatments by checking for healthy grubs in mid-or-late August. If they are lethargic and discolored, they are dying. If their dirty white color is normal, you may need to treat again.
Milky spore is not effective against the grubs we have in New Mexico, so is not recommended. (The Japanese beetle, against which milky spore works, has appeared in Albuquerque but is not yet a major problem.) Diazinon® and Dursban® are no longer on the market.
If you treat successfully this year, the benefits will be apparent next summer, but you may need to treat again
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Grubs in compost 11-00
Q. I have a composter and it is working well. However, there are many, many grubs in the pile. I am afraid to put the compost in my garden or around the yard. Do I need to kill them or will they be okay? I am assuming they are grubs. They are small white/brown worms.
A. Grubs are common in composting material. They are fat, white, larvae of beetles. They have a brown head capsule and legs and a dark gray area at the end opposite their head. There are other "worms" that inhabit compost, so be certain yours are really grubs. Grubs may actually participate in the composting process. There are many types of grubs, so yours may not be a problem. However, it is possible that they are a problem. You should consult with your local Cooperative Extension Service agent for information about the grubs common in your area. If you have a problem, you may use various insecticides labeled for use in the location (vegetable garden, flower garden, etc.) where you will apply the compost. It is also possible to kill the grubs by heating the compost in a plastic bag placed in the sunlight for several hours or days prior to applying the compost to the garden. However, treatment will probably not be necessary.
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How do I get rid of grasshoppers?
Q. How do you get rid of grasshoppers? They are devouring everything but my weeds. Most of the gladiolus flowers never got the chance to open. Now the grasshoppers are starting on my vegetables. Is it too late?
A. Grasshoppers are a yearly problem in New Mexico. If they don't cause problems for you in a given year, rest assured that someone is having problems. This year they are causing problems for many gardeners. Since grasshoppers are capable of migrating from location to location, they are especially problematic. They begin in open land where the eggs were laid. First they feed on grasses and weeds, then when these are gone, they migrate to our gardens. Insecticides can be used to kill grasshoppers, but when used on a limited area such as a private garden or landscape, the effect is minimal. Insecticides will kill them, but new ones migrate in, eat the dead grasshoppers, then proceed to eat our plants. Because the bodies of the dead grasshoppers are eaten, it appears that the insecticide failed. Since new grasshoppers have migrated into the area, our gardens are still eaten. Application of appropriate pesticides to barrier plants around our properties can sometimes reduce the problem by killing many of the grasshoppers before they reach our vegetable and flower gardens. However, some will make it through to the gardens and require treatment there with insecticides or hand picking.
Some gardeners raise guinea fowl, turkeys, or other grasshopper eaters. These can then provide considerable protection from grasshopper damage, even though the fowl will do some damage to fruits and vegetables in the garden. If fowl are used, be sure to select insecticides carefully or, if you prefer, rely entirely on the fowl. Some gardeners use Nosema locustae, a biological control agent for grasshopper control. Products with the Nosema are slow acting and relatively ineffective in controlling grasshoppers once they get larger. Besides, of the many different types of grasshoppers which infest New Mexico, the Nosema is effective with only a few. Of course, not all the grasshoppers we see in New Mexico eat our garden plants, many eat only weeds. Before treating for grasshopper control, be sure they are damaging your garden plants. If you choose to use insecticides, be sure to choose a product labeled for use on the types of plants you have in the garden, and be sure it is for control of grasshopper problems. For your own safety, follow the label directions and be sure to note and follow the recommend harvest interval before harvesting and eating the treated vegetables. Wash all produce with clear water before eating it.
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How to tell if those are killer bees
Q. With all the news about killer bees in New Mexico I am afraid to go out in my garden. How can I tell if the bees on my flowers are killer bees or not? Is it too dangerous to garden here now?
A. First of all, the so called "killer bees" are properly known as Africanized bees. Individually, they are no more dangerous than the common honey bee. Their bad reputation is their more aggressive defense of the hive when disturbed. Unless you have an Africanized bee colony in your garden or a swarm is migrating through your garden, gardening is as safe as ever. Remember that even the common European honeybee can be dangerous if you are allergic or disturb a swarm and are stung numerous times. You can recognize a bee swarm as a large, basketball-sized, mass of bees on the branches of a tree or shrub. Both the Africanized bees and normal honey bees swarm as they look for a place to start a new hive. In any case, avoid approaching or disturbing the swarm. Some beekeepers, with appropriate safety clothing, may be interested in collecting the swarm for their hive farm. After collecting the swarm, they can have samples of the bees inspected to determine if they are Africanized or just regular honeybees.
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Insects appear on houseplants in winter
Q. As I was taking houseplants indoors from my garden where they spent the summer, I noticed that they had no insects. I remembered that this was usually the case, but in the middle of the winter insects would suddenly appear in great numbers. How can they appear suddenly when there are none when I bring them indoors in the fall? What can I do? In mid-winter it is too cold to take them outside and spray them with an insecticide.
A. Even though you don’t see the insects, they are probably there (at least on some of the plants). While houseplants are outside, there are many predators that control the population of insect pests. When we bring them indoors, these predators are usually absent, so natural controls fail to keep pest populations low. When you bring them indoors, there may be small insects under the leaves or in other hiding places. There are probably insect eggs present on the plants.
I called Dr. Carol Sutherland, NMSU Extension Entomologist, about your question. I asked her if the insect eggs were dormant in the autumn like some plant seeds are dormant. She said it was possible, so eggs present on the plants would not hatch immediately but would delay hatching. However, she thought that a more important factor in the appearance of the insects was the slow increase from a few insects in hidden locations to large populations that suddenly seem to become visible. Once the plants with their few insects are indoors, the absence of insect predators allows for steady increases in plant populations.
Some of the most common indoor houseplant pests include spider mites, which are very small and not observed until they have developed very large populations. Aphids and mealy bugs are also common houseplant pests that can easily hide under leaves, between the leaf and the stem or below the soil line. Once populations reach a certain level, they are forced into more visible locations, but by that time their numbers allow rapid population explosions.
This information allows better management of pests. Treat with indoor safe insecticides (insecticidal soap, washing with strong mists of water) to maintain insect populations at low levels, preventing the sudden explosion of insect populations that you have seen in the past. Some insects may require more toxic chemicals treatments, and by treating in the autumn when there are more frequent warm days, the plants may be taken outside for treatment. They can be returned indoors after all the chemicals have completely dried. This is better than waiting for the insect population to explode before beginning to treat and not having the option to take the plants outside for treatment.
Treat the plants for any visible pests before you bring them indoors. Watch very carefully and treat before the pest population becomes large. Always choose insecticides labeled for the pest to be controlled and the environment in which the treatment will be applied. (Do not use an insecticide labeled for outdoor use on indoor plants.) Be sure you understand the label directions and then carefully follow the directions when you treat your plants.
Indoor gardening can make winter much more pleasant for gardeners, but proper management of insects is important to maximize this enjoyment. It is also important for the safety of our families and our plants.
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Insect update: Cold winter had a silver lining
Q. I have noticed fewer aphids on my roses and irises this year. What happened?
A. We finally had a relatively cold winter which killed insects, at least some insects in some parts of New Mexico. This does not mean that we will have no insect problems this year, but in some areas it is delaying the annual explosion of some pests. The absence of the pest species means we may be able to delay control measures, but it also means a delay in the appearance of the natural predators and parasitoids that prey on the pests. Without the presence of the pest, there is no food for these insect "good guys." Continue monitoring the condition of your garden plants. In time, some pest species are likely to appear. Also watch for signs that the beneficial species are present. By being vigilant, you will be prepared to apply appropriate control measures if and when they are needed.
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Japanese beetle invasion 8-98
Q. When I lived back East, we had a bug called the Japanese beetle that was a real problem and was difficult to control. Do I need to worry about it here? I haven’t seen any in the two years since I moved to New Mexico.
A. Bad news! Until last year we didn’t have a problem with Japanese beetles, but then last year one beetle was reported in Albuquerque. Because of the one sighting of this major pest, the New Mexico Department of Agriculture placed Japanese beetle traps in Albuquerque and have trapped 11 beetles this year. That is not good news for New Mexico. Until now we have been able to keep them from the state through regulatory action, import restrictions and inspection of nursery stock. Now, however, they may be establishing themselves in New Mexico to become a permanent pest. Although it is only known to be in Albuquerque at this time, if the beetle does successfully establish a reproducing population, it is very likely that it will spread through the irrigated valleys and jump to other irrigated areas as people move from place to place. In managing a problem through Integrated Pest Management, it is important that we survey the extent of the problem, so we are asking your help. We need to know how widely the Japanese beetle has spread in New Mexico.
Don’t start treating for the Japanese beetle until you are certain the beetles that you see are actually the Japanese beetle. If you capture a small beetle with metallic green or copper on its upper surface and notice chaffing damage to the leaves of plants in the rose family, roses, apricots, apples, raspberries, or any of the many other rose relatives grown in New Mexico, you may have the Japanese beetle. Dr. Carol Sutherland, NMSU Extension Entomologist and State Entomologist for the New Mexico Department of Agriculture asks that you take a specimen to your local Cooperative Extension Service office. Remember that this is a small beetle, only the size of your little fingernail. The Extension agent can have an inspector from the New Mexico Department of Agriculture confirm the identity of the beetle. If it is indeed a Japanese beetle, then you should probably begin to apply treatments to stop its spread in New Mexico and to protect your garden and landscape.
As you collect specimens, don’t be confused by the large metallic green June beetle which is native to New Mexico. These are the large buzzing bugs which seem to dive bomb you. This beetle is at least three-fourths inch long and much larger than the Japanese beetle. It does little damage and should be no cause for concern. It is not necessary to take a sample of this one to the Extension office.
If it is confirmed that you have Japanese beetles in your garden or landscape, there are many products, some organic, some synthetic chemicals, which may be used to manage the infestation. Ask your local garden center or County Extension Agent for recommendations. Be certain the product you select is labeled for use in the location you intend to use it - garden, lawn, ornamental beds. Also, follow all directions in the use of the product to maximize effectiveness and minimize hazards to yourself and the environment.
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Japanese beetles - a NM threat 8-97
Q. We may have a new pest in New Mexico. The Japanese beetle has been a problem in eastern and north central states for a long time, but its presence was confirmed for the first time in New Mexico this summer. Will you and the readers of "Yard and Garden" assist the New Mexico Department of Agriculture in surveying for additional occurrences of the Japanese Beetle in New Mexico?
A. This is an alert as well as a call for assistance. According to Dr. Sutherland, NMDA entomologist, we have been fortunate that the Japanese beetle has taken so long to show up in New Mexico. In states where the pest is established, production of nursery stock and turf are highly regulated by state and federal agencies in an effort to curb its spread. We are asking for your help in monitoring in New Mexico to prevent it from gaining a foothold here. If you find beetles in your garden which fit the description of the Japanese beetles presented below, please collect a sample, kill it in a leak proof container of rubbing alcohol, and take the specimen to your local Cooperative Extension Office along with a label including your name and the street address where the specimen was collected. This information will be sent to the New Mexico Department of Agriculture to verify that it is a Japanese beetle and to allow them to track this new pest in New Mexico. Your assistance will be greatly appreciated. According to Dr. Sutherland, the Japanese beetles do not bite or sting, but the short spines on their legs may feel prickly. You may prefer to use a cup or jar to capture the beetle. The Japanese beetle has been a major pest of landscapes and fruit trees in the U.S. since it was first introduced around 1916. It has severely damaged lawns, golf courses, pastures, shrubbery, flowers, and fruits. It is described as one of the most destructive of garden pests and has over 300 species of planthosts.
The beetles are gregarious and can be found in groups of 20 to 30 beetles which quickly defoliate a plant and decimate a landscape. The juvenile forms of this beetle are grubs which live underground feeding on the roots of grasses as well as many other plants, weakening and killing them. The adult beetles may be recognized as colorful insects with a metallic blue or green pronotum, the area between the head and the wings; one color variant has a metallic copper head and pronotum. The wings are coppery in color. They have two conspicuous white spots and several smaller spots near the end of the abdomen. They are quite active during daylight hours. According to Dr. Sutherland, they are good flyers, but lousy landers. Their ability to fly should increase our apprehension regarding the spread of this pest through our landscapes. To distinguish between Japanese beetles and May and June beetles, the Japanese beetles are about one-half inch long while the May and June beetles are five-eighths inch or more in length. The May and June beetle also lack the white spots on the abdomen. The grubs resemble the familiar white grubs (larvae of the June beetles) which New Mexico gardeners have known for some time. However, the Japanese beetle is a greater threat to our gardens than the May and June beetles.
During the warm season the grubs reside near the surface in the soil, feeding on plant roots. When the soil is cool in the winter, the grubs burrow six to twelve inches deep and construct earthen cells in which they pass the winter. In the spring they return to the surface, feed for a few weeks, then form their pupal stage which lasts for about six weeks. The adult beetles then emerge to feed on our gardens and landscape plants.
Dr. Sutherland states that there is usually one generation annually with adults emerging from their pupae from mid-May through mid-August. If it becomes necessary, control may be accomplished by application of appropriate insecticides. At this point in time we need to determine if there are more Japanese beetles in New Mexico and where they are located. The beetle confirmed thus far may have hitchhiked on nursery products originating in an infested area. If so, we may have no need for control efforts. Or, it could indicate a bigger problem. In that case, insecticides labeled for control of beetles may be needed. Spores of milky spore disease are sold under several trade names. Although they are ineffective against our common May and June beetles, they may be used successfully to control Japanese beetle larvae. Hand picking adults, knocking them into jars of kerosene and water can also be helpful. If infestations are severe and you cannot wait for the milky spore disease to work, or your timing is wrong, there are other insecticides labeled for control of beetles and grubs. Be sure you choose an appropriate product for control of Japanese beetles on the plants they are affecting and then follow the directions on the label.
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Juniper insects killing twigs
Q. There are a lot of branches dying on my pine trees. It is not the whole branch that dies, but only the six inches or so at the end. What can I do to solve this?
A. The sample you sent was of juniper, not pine. I am aware that many people call all evergreen conifers "pines," but in this case it is important to recognize the difference because different pests infest pines and junipers. In your case the problem is either a beetle called the juniper girdler or a small caterpillar called the twig pruner.
A little information about your potential pests. According to Bob Cain, NMSU Extension Forest Entomologist, the twig girdler feeds in the phloem and cambium zone under the bark of the twig before moving to the pith in the center of the twig. The twig pruner goes directly into the pith and feeds there. Bob states that these insects are more common in forested areas than in the urban landscape, but occasionally there will be problems in the home landscape. The management treatments recommended by Bob Cain are the same for both insects. He recommends that you remove the branch tips as they die. There is no effective chemical control recommended and the damage done is usually only cosmetic. The form and density of the juniper is not altered significantly by these insects.
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Pine tip moth control 4-02
Q. I have had problems over the years with pine tip borers on my ponderosa pines. When should I spray and what should I use?
A. Over the years we have discovered that the best time to spray for pine tip moth in Albuquerque has been the first full week of May. The appropriate dates will differ in other parts of New Mexico. Some people spray a little before that (the last week of April or so) and have good luck since many of the chemicals used have a residual effect long enough to allow this. If you spray later than the announced date, you may still kill the pine tip moth larvae, but they may have already done damage to the pine shoot tips, so the tree’s first new growth may die. The tree will produce more buds in response, but if this happens every year, the shape of the tree will suffer. If you spray late, use a chemical that is systemic (will be absorbed into the tissues of the tree). The usually recommended products for homeowners are Cygon™ and Orthene™. Some licensed spray companies use other products such as Talstar™ that is more benign in the environment for mammals and birds but, because it is very toxic to fish, is not available to the public. This product is not systemic, so timing is critical. If you have birds nesting in the trees, you may want to consider hiring someone to spray this product.
Tree size is another factor to consider according to NMSU’s Extension Forest Entomologist, Bob Cain. He advises that any tree over 15-feet tall doesn’t need to be sprayed. The moth larvae will infest the lower branches but will not bother the "central leader" sprout, the sprout responsible for the upward growth of the tree. Therefore, they will not harm the appearance of the tree and, for a tree at that size, are not likely to seriously deform the tree.
The reason we have this information in Albuquerque is that Master Gardeners have worked with the NMSU Cooperative Extension Service for almost 20 years to collect the data needed to properly deal with pine tip moth. In other parts of New Mexico, this data is not available.
Bob Cain identifies Ponderosa, Afgan, Austrian, Scots, Mugho, and Japanese black pines as trees most likely to be affected by pine tip moths. He says that pinyon pines and the five-needle white pines are less likely to be seriously damaged.
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Pinon sawfly control
Q. The needles on my pinon trees seem to be eaten. Most of the needles on several branches are totally gone, or eaten down to stubs. There are some little worm-like things that seem to be causing the problem. I have sprayed with Bacillus thuringensis because I don't like to use chemical insecticides.
A. Dr. Bob Cain, NMSU Extension Forest Entomologist, said that the pinyon sawfly is active now. It can occasional strip the all the needles from the tree, but more often only strips the needles from one or two branches. These larvae are the juvenile form of a sawfly, in the order Hymenoptera, the wasps, ants, and bees. The sawfly is not the larvae of a moth or butterfly, it is not in the order Lepidoptera, the moths and butterflies. Bacillus thuriengensis (BT) is effective only against members of the Lepidoptera, so the Bacillus thuringensis is not effective against sawflies. Since you prefer not to use chemical Bob recommends that you blast them out of the tree with a strong jet of water. Most of these insect larvae will not successfully return to the tree. Those that do succeed will be dispersed through the tree and the damage will be much less apparent. If you have ponderosa pines, Bob says that there may be some sawfly on them as well. The water jet method of sawfly management is the first line of defense against this pest for homeowners. If the infested trees are large or the infestation is more extensive, some may wish to use chemical insecticides. In this case, contact your local Cooperative Extension Service Office for recommendations of appropriate chemical controls.
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Pitch a sign of piñon tree borers?
Q. A man stopped at my house and told me I had borers in my piñon tree. He showed me that there was a lot of pitch coming from the tree. He even opened a ball of pitch and showed me the worm inside it. He told me that I had to have the tree sprayed or the borers would kill it. Did I do the right thing?
A. Based on the description of the worm, spraying was probably not necessary. Piñon trees are prolific producers of pitch. Pitch is used to close wounds in the bark to prevent water loss. Wind cracks caused when the tree bends and twists in the wind are sources of pitch. Insect attacks also stimulate pitch production. If an insect is involved, especially the one you probably saw, the pitch will probably have a yellowish or pinkish color. If it is due to wind or growth cracks in the bark, the pitch will first be crystal clear, drying to a frosty white, and with age turning brownish. Some of the pitch you saw was probably due to cracks in the bark, but there was obviously an insect involved as you saw one dug from the pitch. The pine pitch moth and the pine bark moth are the likely candidates. They are not true borers and cause relatively little damage to the tree. They injure the bark a little to stimulate production of pitch. They make their home inside the pitch and feed on the pitch. Insecticides cannot penetrate the pitch and systemic insecticides do not enter the pitch; therefore, spraying is not recommended. Besides, there are not insecticides labeled for control of these insects. If the tree is heavily infested, there may be other underlying problems. An unhealthy tree is more likely to be injured than a healthy tree. Proper planting and culture are the most effective means of preventing the pitch moth or bark moth from causing major problems.
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Pitch moth infestation 5-02
Q. I have a relatively large pinyon tree that appears to be infested with either the pine pitch moth or pine borers. In digging around in the cloudy, pink pitch, I’ve found insects that resemble worms or larvae. The tree’s health seems to have declined over the past few years. Your past comments regarding the pitch moth larvae indicate that it’s not particularly harmful to the tree. How can I tell the difference between the pitch moth larvae and borers?
A. Your description of pitch moth or bark moth larva is good. These are not true borers because they only bore into the bark, not the wood. Their purpose is to cause the tree to produce pitch, as you see your tree doing. Borers will feed in the cambium and phloem tissues under the bark doing much greater damage than the pitch moth larvae which feed on pitch. The borers will not be found in the pitch nodules, but the nodule of pitch is the place in which you will find the pitch or bark moth larvae. The pitch provides both a "home" and supply of food to these larvae.
Unless the attacks are numerous and repeated, the pitch and bark moth larvae do minimal damage to the trees. Smaller trees are more severely affected, as are trees that are under stress. In our current drought, there are numerous trees suffering from stress. Good tree maintenance, proper irrigation, and pruning are the best means of protecting the tree. There are no insecticides labeled for control of these pests. As you have pointed out, the damage is not a great concern in a healthy tree. You can carefully remove the insects manually by digging into the pitch nodule, but don’t increase the damage by cutting into the bark. Heavily infested branches may be removed if that will not damage the form of the tree, but it is rarely necessary to prune the infested branches from the tree.
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Roaches killed with boric acid? 6-02
Q. I read that boric acid can be used to kill roaches. Can I use boric acid in my flower beds to keep the roaches from coming indoors?
A. Boric acid is effectively used as an indoor treatment for roaches. Use only boric acid whose container is labeled for roach control. As roaches crawl through an area treated with the powdered boric acid, it collects on their legs and body. As the roaches later groom themselves, they will ingest the boric acid and die. Boric acid is intended for indoor use, not outdoor use. Boric acid can kill your plants as well as it can kill roaches. The boron in boric acid is a nutrient needed in very small quantities by plants. Even a little too much boron is toxic to plants. Most of our Southwestern soils have adequate concentrations of boron, and additions of boric acid can quickly create a toxic situation. Warning: Ingestion or inhalation of boric acid by humans or pets is harmful and may be fatal. Pets who walk through boric acid typically lick enough off their paws to be poisoned.
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Scale problems on weeping fig
Q. I have a weeping fig tree, and I know it has scale. I have been treating it with rubbing alcohol wherever I see it. Now my plant has a sticky residue on its leaves. It even drops this stickiness on the floor. Is this the scale working or what is it?
A. What you have described is the accumulation of "honeydew," a syrupy material produced by the scale insect, and other insects, as a byproduct of consuming the sap of the infested plant. This is an indication that the problem persists in spite of your treatments. You may want to purchase an insecticide safe to use indoors but labeled to control scale insects.
Consult your local nursery or local Cooperative Extension Service for an appropriate product. Perhaps you will choose to discard the plant to prevent the infestation from spreading to other houseplants.
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Spider mites on avocado 10-00
Q. I have a 12-year-old avocado tree. It has spider mites. What is the best way to get rid of them? I’ve been battling them for about 6 years.
A. In our climate, an avocado is an indoor plant, so it will be important to use pest management practices that are useful indoors. If your tree is in an area with a tile or concrete floor (a floor that will not be damaged by water), spraying frequently with water may be sufficient to keep the mites from doing damage. They will survive, but their populations will remain low enough to be non-damaging. Smaller plants may be moved outdoors when the weather allows so that they may be sprayed with water. Larger plants on platforms with casters may also be moved outdoors and sprayed.
The benefit of using water is the non-toxicity of the water to the person doing the application and the lack of potential damage to the plant. Insecticidal soap should also be useful. It may be damaging to some plants (read the label for warnings), and some people are allergic to the soap. Soap may also be damaging to carpets, curtains and upholstery, so the plants must be in an area without furnishings which may be injured when the insecticidal soap is applied. Use of water sprays or insecticidal soap on a frequent basis should keep the spider mites at bay; however, if the infestation is too severe, you may choose to apply a miticide labeled for use on ornamental plants. Such products must be applied out of doors when the weather permits. Read and follow all label directions.
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Too late to spray for pine tip moth 8-00
Q. I sprayed my small Ponderosa Pines in May of this year for Nantucket pine tip moth. Last year I was told that I should also spray in July, when the notice from the state agriculturalist came out, and I did. This year I didn’t see a notice in July. Did I miss it? Is it too late for spraying to do any good? I do notice some pine tip moth damage on my small trees. Will this damage continue or spread if I don’t spray?
A. Yes, it is probably too late to have maximum effectiveness in spraying for pine tip moth. In some parts of the state, you may be able to kill the young developing larvae inside the pine shoots which the larvae has already killed. The damage to be done by the moth larvae has already been done, so you will do little that benefits your tree. In most of the state, you will probably have no effect on the larvae, so you will waste money and be exposed to some rather potent chemicals (depending on which you choose to use) without doing anything to benefit the tree. It would be best to wait until spring to spray.
You didn’t say where you live. The information about proper timing for pine tip moth spraying is only available in a few larger cities in New Mexico, and it is important that the timing be appropriate for your area. Areas without the notifications usually don’t have Nantucket Pine Tip Moth problems, so I assume you are in Albuquerque, Santa Fe, or Las Cruces where this information is most common. In any case, I suggest you wait for the first announcement from the Cooperative Extension Service, and spray according to directions at that time. Contact your local Cooperative Extension Office to determine how the information will be disseminated so that you will not miss it.
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Ugly little spiders
Q. I have little ugly spiders in my pine tree. They are baby spiders with long legs and group together in bunches on the twigs. What kind of spider is it and what can I do? Are they dangerous?
A. The samples you sent are not spiders - they are aphids with long legs. These aphids are a type of aphid which infests pine trees and causes some problems. First, if you wish to investigate and look at the aphids in the tree, be sure to wear safety glasses. A few years ago I spoke to a gentleman who, when looking closely at these aphids, forgot that pine needles have a sharp point. He pierced his eye with the pine needle. Fortunately, beyond the pain and a period of healing, he had no permanent damage to his eye. The aphids feed by piercing the stem of the pine with a stylet mouthpart. This is then used like a soda straw to draw "sap" and nutrients from the plant. As the sap has an excess of sugar from the aphids' perspective, they excrete a sugary syrup, called honeydew. This is the mist of droplets that make windshields of cars sticky and create a problem for car paint. You may notice "wet" patches on sidewalks under pine trees where this syrup accumulates.
Besides being a nuisance for owners of cars parked under pines or people sitting on chairs or benches under the trees, the aphids are robbing the trees of the sugars and amino acids that they have synthesized from sunlight, water, and carbon dioxide. These materials were made to feed the tree, not the aphids. So, the trees are injured as they have lost some of their food supply. As this honeydew accumulates on the leaves and twigs of the tree, a fungus, sooty mold, begins to grow, using the honeydew as a food. The sooty mold doesn't hurt the tree except when heavy amounts develop and block sunlight from the chlorophyll of the leaves. In this instance the sooty mold can then reduce photosynthesis and the ability of the tree to synthesize the food it needs.
Now regarding your question, "Are they dangerous?" - the answer is that they are not particularly dangerous. Of course a messed up windshield on a car can cause traffic dangers, but the aphids do not injure people, only plants. The next question to ask is should you do anything about the aphids. The answer is one you must answer for yourself. If you see great numbers of aphids on many of the twigs in the tree, you may choose to treat to reduce the aphid population and limit the damage to the trees. If the honeydew is causing problems, you may also choose to treat. However, if you find numerous lady bird beetles or lacewing larvae in the tree, you should allow the natural controls, these insect predators of aphids, to do the job.
If you decide to treat, you may use a strong jet of water to wash many of the aphids from the twigs if the infested branches are within range of a strong stream of water from the garden hose. You may also use one of the insecticide products available at your local garden store. Be sure to select a product labeled for control of aphids on the pine or other trees you have found infested. Read and carefully follow the directions on the label when applying any pesticide, even "organic" or natural pest control products.
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Wasp removal 11-00
Q. Is there a humane way of removing hornet nests from eaves? I would rather not shoot the nests with those chemical sprays that are available, but the nests are accumulating around the eaves of the house.
A. You are probably describing the paper wasps which often build their flattened, dish-shaped nest under the eaves of our homes. According to Dr. Carol Sutherland, NMSU Extension Entomologist, the weather has been cold enough in most of the state to drive the wasps from their nests. They have taken winter refuge in various hiding places (attics, cracks and crevices in your house and surrounding structures, as well as under rocks and mulch materials). They will return to the nests in the spring, but now in their absence you may remove the nests with little worry about the wasps stinging you. Dr. Sutherland stated emphatically that this is not true of honey bees. They persist in the nest all winter, so don't apply this advice to bee removal. Next spring the wasps will emerge from their winter hiding places and return to the nests or to the sites where the nests once existed. At that time, you may need to take some action to discourage nest reconstruction.
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Wasps and hornets in shed
Q. I have a nest of what seem to be (feel like) hornets in my shed. How can I positively identify them and what should I do about them?
A. Hornets are a possibility, as are wasps (paper wasps who make their nest from a paper-like material). If you want to identify them, you will need to collect a dead example and take it to your local Cooperative Extension Service office. The Extension Agent should be able to identify it for you or he can send it to the NMSU Extension Entomology Specialist for identification and recommendations. Getting the sample may be a major trick as I am sure you don’t wish to be stung again. Perhaps there is a dead specimen just outside the shed or inside the door where it is safe to collect it. Otherwise, you might wish to use a spray to kill them, and then collect a sample. The hazards when spraying are the same - don’t let them sting you!
The hornets and wasps are least active when the temperature is lowest, that is, early in the morning about the time the sun rises. They will be slowest at that time, but since it is summer they may still be capable of flying, chasing, and stinging you.
There are special aerosol wasp and hornet sprays made for the purpose of treating wasp and hornet problems. The aerosol container of insecticide produces a narrow stream that can be directed at a wasp or hornet nest from a relatively great distance (relative to using a fine mist spray which requires that you be quite close to the target). If the wasp (hornet) nest is just above the entry door into the shed, the distance that the spray can be dispensed is not as relevant. The problem here is that a wasp or hornet nest in this location gives you no safe place from which to use the insecticide. If the contents of the shed will allow use of an aerosol insecticide bomb, then that may be a safer way to treat the problem. Be certain there is no flame or potential for a spark which could ignite the fine mist of insecticide. A fine mist of dishwashing liquid (about 2 tablespoons/gallon) is often effective at knocking down wasps and bees. This, used with a medium-fine mist from a pesticide sprayer, may allow you to get at wasps and hornets over the entry to the shed.
In any case, plan your escape and be certain that there are no obstructions to running for shelter indoors when they begin to pursue you. It would also be wise to have another person handy in case you have an allergic reaction to any stings and need medical attention. You might want to purchase a "bee suit" (contact some of the pesticide distributors), or you may find it easiest and safest to hire a professional pest control operator (exterminator). This last suggestion is definitely the safest for you. Be certain the exterminator is reputable, licensed, and insured. Finally, remember that wasps and hornets have some beneficial characteristics. They eat other insects which are pests in our landscapes. However, even though it is beneficial, it can be painful and even dangerous to be stung by these insects.
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Web worm problems in fall 11-99
Q. All over the valley large healthy trees are being attacked and destroyed by web worms. At first limited to Lombardy Poplars and cottonwoods, they can now be found on sumac, pecans, fruit trees, ashes, and in general most broadleaf deciduous trees. Some trees (poplars) are completely shrouded with webs, and there is probably little chance of those trees surviving. Most affected branches are very high up on the trees and hard to reach with sprayers or pruners. What is the best way to control web worms?
A. The ability of trees to survive difficult conditions is amazing. The insect you described is the fall web worm which appears to be doing tremendous damage. I was in Las Cruces and saw first hand what you have described. It does indeed look bad; however, but after talking with entomologists, I am assured that the damage will be minimal. Dr. Carol Sutherland, NMSU Extension Service Entomology Specialist, assured me that the web worm only feeds on leaves and doesn't harm the bark or the buds. Since this is the end of the growing season, the leaves have completed the greatest part of their work; that is, the production of food to sustain the growth of the tree. While there is a little growing season left, early loss of leaves at this time does not harm the tree excessively.
Web worms in the spring and early summer can be much more damaging, but the fall web worm seems to have a "contract" with the tree not to attack until the damage is minimal. The level of infestation in Las Cruces is extreme and suggests that next year you should prepare to treat. It is too late to treat with chemicals now. Chemicals will have very little effect. Next year in August, as the caterpillars are just developing and before there is much development of webbing, you can apply any of several insecticides labeled for control of moth and butterfly larvae. This even includes some organic insecticides. Early in the life of the larvae, they are very susceptible to insecticide and may be controlled.
You alluded to physical removal of the caterpillars by pruning in addition to spraying. If it is possible to reach them, if the pruning will not damage the form of the tree, and if you will not remove too much of the tree by pruning, then pruning may be an effective means of reducing the problem. Often, however, we do more damage by pruning than the caterpillars have done. Burning the webs from the tree will definitely do more harm than the caterpillars and is not recommended. Besides, this can cause damage to homes and other structures if the fire gets away. The best thing to do is wait and tolerate the fact that the web worm is a nuisance.
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What are these eggs? 2-02
Q. I’ve been wondering what bug leaves eggs that look like cantaloupe seeds? They are laid in a neat row, layered over each other, and I have found them on my geraniums as well as on various garden plants, including my plum tree. P.S. I enjoy your TV show every week.
A. You have described katydid eggs. These are tan in color and usually placed in a double row of overlapping eggs. Here in New Mexico the katydid is not considered a significant problem. We consider it an interesting, green, grasshopper-like critter in the garden. So, in New Mexico, control is not usually necessary. In other parts of the country it can be a problem which requires some effort to manage. Be thankful that you are in New Mexico and can just enjoy the katydid.
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White fly control 10-00
Q. What can I do to get rid of white fly? Everything in my (small) yard is infested, including marigolds, tomato plants, zinnias, snapdragons, etc. As soon as I start watering, a cloud of white flies rises from the plants being watered. There are trees in the area (Ash, Jacaranda, Mexican Elder, etc.) but not in my yard. I would appreciate any suggestions.
A. There are several insecticides labeled for use in managing white fly infestations. Some white flies have developed resistance to some insecticides, so you might have to try several. Insecticidal soap will be effective but may do some damage to the plants. Horticultural oils may also be effective, but read the label to be certain that they may be used on the plants that are infested. Malathion®, Diazinon® and other insecticides may also be tried. It is important that you read, understand, and follow the label direction for any product that you choose.
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Beet leafhopper, curly top virus outlook 4-03
Q. Do you have a "prediction" as to how the leafhopper population is this year regarding curly top virus in tomatoes? I have several tomato plants under water shelters and will be planting several more in the next week or so.
A. Extension Service agents around New Mexico report that there is quite a bit of mustard weed. These weeds serve as winter host to the virus and spring host to the beet leafhopper. They germinate in the fall and become infected with the curly top virus, then host the virus through the winter without being injured themselves. They also serve as shelter and food for the beet leafhopper that carries the virus from plant to plant. Therefore, the potential for curly top virus is fairly high in New Mexico this spring.
To minimize the problem, eliminate the mustard weeds. This will reduce the possibility of problems. You may also wish to wrap the tomato cages with cheesecloth or white row-cover fabric to exclude the leafhopper. Light and air can penetrate the covering, so the tomatoes grow well under the slight shade. You can unwrap the covering to harvest tomatoes and re-wrap it to continue the protection. If the tomatoes outgrow the cages and covering, then remove the covering. If the plants get the virus, you can still harvest any tomatoes that have formed.
It is important to remember that the curly top virus does not infect plants directly from the soil or from compost. For that reason, it is safe to compost curly top infected tomato plants and to plant tomatoes near areas of the garden that had curly top problems in previous years. Spraying insecticides to kill the leafhoppers provides little benefit. The insecticide often excites the insects causing them to spread the disease before dying. Weed management and preventing insect access to the plants are the best ways to reduce the potential for curly top virus problems.
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Thrips on irises 5-03
Q. Please give me advice on eradicating thrips. They appear annually on iris blossoms and then disappear. I have tried several things to no avail. I sprayed as the blossom stalks emerged and have kept the beds free of debris.
Do thrips cause water spots in the iris blossoms? If not, what is causing this damage? It is not overhead watering as I show irises and take great care not to water from overhead.
A. Thrips may cause the "water spots." They feed with rasping mouthparts that scrape the flower petals and leaves of many plants, including irises. The result is areas of petal without color pigments appearing as water spots. There are other causes, as you alluded, such as overhead watering. Since you are aware that you have a thrips infestation, that infestation is the likely cause.
You are familiar with thrips, but other readers may not know this pest, so I will describe it. A thrips (this is the correct spelling for singular and plural) is a small yellow, brown, or black insect, often not noticed by gardeners. They are less than 2 millimeters (about 8/100 inch) in length, so often are not noticed, but their damage is very noticeable. They are long and narrow, feed by rasping the plant cells and drinking the juices that escape through the wound. This is what causes the damage. There are many species of thrips, each having a wide host range and being a problem for many plants. Rose growers, like iris growers, have tremendous problems with thrips infestations. Even though they are small, a careful inspection of the flowers, especially light colored flowers, will reveal small, narrow insects crawling around on the petals (and sepals), especially into the folds of the flower where they are protected.
As you have described, treatment is difficult. They are weak flyers but blow easily in the wind. They may build up populations in many plants, lawns, grain fields (which you have in the Roswell area), and in weeds (we have a lot of weeds this year). As their population increases or the first host plant matures (weeds are drying now), they migrate to other plants. Because they migrate into our home gardens from other areas, treatment of a single garden may not be effective, but we should take measures to protect our plants.
Disposal of spent blossoms helps remove thrips. There are insecticides (organic and synthetic) that are labeled for thrips control, but there are natural predators that feed on thrips. We often see thrips damage early in the year. Damage declines as the natural predator population increases. Use of insecticides may prevent the build-up of the natural predators and may actually prolong the period of thrips activity. Enclosing special (show) plants in cages wrapped with spunbonded row cover fabric will help exclude the thrips, limiting damage to the plants until the thrips population drops.
If you choose to use insecticides, there are spray applications and systemic materials labeled for thrips. Please read the label and follow the directions exactly. While you will be killing some thrips, others will migrate into your garden and do some damage before they are killed.
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Aphids on Arizona ash 5-03
Q. My Arizona ash tree is about 9 years old. This year is really bad compared to last year with this: The leaves are curled up with white stuff in them. The tree is dripping and dropping white stuff. Can you tell me what it is, and can I spray it with anything?
A. What you are describing is an aphid, a small insect that feeds on the young leaves of the ash tree causing its leaves to curl. They are present only a short while, do little damage (more nuisance than anything else), and by the time you get around to spraying, they are gone. The white stuff you describe is their shed skins (insects grow by shedding their outer exoskeleton - skins). If there are still some active aphids in the leaves, the best treatment is to wash them with a strong jet of water. This will often cause some of the aphids to fall out of the leaves. There are many predator insects that eat aphids, so use of insecticides will probably do more harm to the predators than to the aphids.
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Scale insects on a ficus 9-03
Q. My indoor ficus leaves and branches have sticky brown lumps. What is wrong? What can I do?
A. This is a good description of scale insects on indoor ficus (Ficus benjamina, F. retusa, F. indica, etc.). These damaging insects may also infest other houseplants, so it is important to manage the problem and prevent their spread. This topic has been discussed in Yard and Garden before, but it is an important consideration at this time of the year as we are beginning to bring houseplants indoors after a summer outside.
The sticky substance is the honeydew excreted by the insects. The bumps are adult scale insects under their waxy coverings that make them difficult to treat with insecticides.
There are a variety of treatment options available - some treatments preferred by one author, others preferred by another author. Chemicals are most effective when used to treat the juvenile (crawler) form of the insect before they have formed their protective covering. At this time horticultural oil and insecticidal soaps are very effective. (Both have very low toxicity to mammals!) These products can stain fabrics, so cover carpets, upholstery, and draperies if you apply these (or any other product indoors). Some authors recommend use of systemic insecticides to kill the adult phase of this insect. Contact insecticides are ineffective because of the scale’s protective covering, but systemic insecticides are absorbed into the plant and then into the insect when it feeds on the plant juices. This product is more toxic to us and our pets, so it is safest to apply it outside and leave the plant in a shady location until the chemical has dried.
Some authors prefer to recommend use of mechanical control methods. They dip a cotton swab into alcohol and rub firmly enough to remove the insect (covering and all) from the stems and leaves. Some scale insects will rub off quite easily while others will require more effort. Take care not to bruise the plant when doing this.
As I mentioned, this is a good time to be checking plants for insects and diseases before bringing them indoors. If they have been indoors, it is still warm enough to take them outside to a shady location to clean them up before their long winter stay indoors. Plants that are severely infested with insects may be treated (mechanically or chemically) so that their problems will not spread to other plants, or they may be discarded and replaced with healthy plants from a nursery. New plants from the nursery should also be carefully inspected for diseases and insects. Problems are more easily treated now rather than in the middle of the winter when it is too cold to take houseplants outside for treatment.
If you wish to learn more about scale insects there is helpful information about scale insects and various treatment methods at the Texas A&M web site at http://theurbanrancher.tamu.edu/bugs/b6097.pdf.
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