Outdoor Pest Questions: Insect Control
Q. The problem is that we seem to have thousands of flies in our garden, on some of the small trees, on the wisteria, on the front of the house and indeed around some windows on the house itself. It is driving our dog and us mad. Is there anything that we can do or plant that will either get rid of them, or coax them away? I have been told that they are due to the sap rising in various plants. Can I assume that they will disperse on their own accord when everything is in full bloom?
A. The first fly that comes to mind with wisteria is the mealy fly (Mealy flata), a white fly. These are often found on wisteria. A large lantern insect, the mealy fly is a sucking bug. You can find white masses of waxy eggs on backs of stems. They are just attracted to wisteria, but can be found on many plants and shrubs. Adults present themselves in August and September. You can spray insecticide soap or a chemical like Malathion, or one registered for use in your area. There are also systemic controls that can be applied to soil. For approved chemicals in your area, consult with your local Dept. of Agricultural Extension Agent.
You certainly do not want to harm a helpful fly, such as the hover flies, which are extremely important insects in organic gardening and organic pest control. The hover fly is a garden helper that pollinates plants and their larvae feed on small insect pests like aphids. The hover flies are easily spotted because of their bright colors, striped in bronze, gold, and yellow, resembling bees and wasps. They dart among flowers and lay eggs among clusters of aphids, mealy bugs, mites, scale and other pests where their larvae can feed. Adults do feed on nectar and pollen, especially on daisy-like flowers where their short tongues can easily access their meals.
Identification of the type of fly that presents itself as a pest in your garden should be a first step before taking any control measures. Flies come in all flavors and colors, and it is important that you know what fly you are dealing with. Contrary to popular belief, many more bugs help us than harm us. It is up to us to determine if it's good or bad bug.
Q. I need some help on how to kill mosquitoes from my yard. I have removed all standing water and I keep the grass cut low but I have a lot of evergreens, several bushes and flowers as landscaping. The bugs are bad any time of the day, but get worse at sunset. We must soak ourselves in repellent every time we go outside. We also have been confirmed of having West Nile disease in our area from dead blue jays to nighthawks just from our yard. Will a "bug zapper" light work against mosquitoes?
A. Bug zappers attract moths, bees and flies more than mosquitoes. Any that do get zapped just happen to be in the area. Bug zappers do not distinguish between desired insects and the pests, and will kill most if not all. If you live in a less populated area and do not have neighbors nearby or if your neighbors do not mind chemical pesticides, fogging with insecticides will knock them down and keep them at bay for at least a few hours, but as soon as there is a breeze to blow the residual away, new mosquitoes will re-invade.
Citronella candles and mosquito coils seem to help when the air is calm, but their effectiveness diminishes with a breeze. If you can increase air circulation and decrease shade, that would help deter them from seeking shelter from the sun in your shrubs. As you have indicated, eliminating any standing water will stop breeding in your area. If you have a pond or water feature, keep the water moving with a pump and maybe even add fish to eat any larvae that do develop.
Q. I noticed patches of my lawn were thinning and yellowing and mounding slightly upward. Then I finally noticed that it was a very large ant complex, not the little mound of dirt that the small brown ants leave, but a huge metropolis of larger black ants. Now this year they have spread and have made the lawn look terrible. What can I do about this? I am somewhat of an environmentalist and I have never used insecticides or weed killers, but I am willing to make an exception in this case.
A. Try Diazinon granules. The product is easy to use and has a good residual life. It will take care of the ants and other insects that are damaging your lawn. Please read the label directions for more info. In addition, most granules require that you water them and Diazinon can be hazardous to pets and children. Always read and follow product label directions and take all precautions. Not all chemicals are available in all areas. Call your local Dept. of Agriculture Extension Agent to learn what is recommended and available in your area.
Q. We have a new house with new vinyl siding. We have a lot of spiders living on the sides of the house - I means LOTS of spiders - and they soil the siding with their droppings. Other nearby houses are experiencing the same problem. Is there an insecticide that is safe to use on vinyl siding? Also, it is safe to pressure wash vinyl siding or will you push water up under the siding using a pressure washer?
A. Vinyl siding can be pressure washed. Too high pressure can force water under siding. Many prefer to use a water hose and brush to clean, starting at bottom and working their way up. Spiders tend to be active where they find other insects upon which to feed. Many of these are attracted to the lights on exterior of home at night. Turning off porch lights and drawing curtains at night to make home less attractive to moths and other insects attracted to light will tend to keep spiders at bay.
Keeping spider webs knocked down will also minimize spiders on the outside of the home. You can apply insecticide around doors, windows, and vents, outside stairwells, window wells, along the foundation, and under the lip of the siding. Spider and insect control on the exterior of the home helps keep the spider population down indoors. 100 percent control usually is difficult to achieve, because spiders can walk over the top of a surface that has been treated with insecticide and not accumulate enough to affect them. Removing heavy dense vegetation along the perimeter of the home is also helpful.
Q. I have a star magnolia that has been infested with magnolia scale. My research has turned up a few remedies that are appropriate for use late in the summer when the scale is in the crawler stage. However, I would like to know if there is a way to rinse the honeydew from the scale and the associated black soot mold from the leaves of the magnolia. The honeydew is attracting an enormous number of bees and wasps, making the walkway past the magnolia downright dangerous.
A. The scales are usually about 1/2" long and oval. Typically, they look white, but honeydew and sooty mold may result in different colors but may appear white due to a waxy "bloom." You will see honeydew and sooty mold on infested plants. This scale occurs mostly on magnolia, but can be found on tulip trees. Females give birth to live crawlers in early September. There is one generation per year.
Prune out infested limbs. Scrub off with a stiff brush what you can. Horticultural oil sprays kill primarily by smothering, so they will be less effective against scales crowded together or occurring in layers on the plant. Insecticide soaps provide a new alternative. They are very effective against both active and settled crawlers. Oils and soaps are safe to use and are especially good choices for sensitive areas, such as where people are present soon after treatment. Because of their short residual, they help to conserve beneficial species. Oil and soap sprays are important, so you need to plan for lots of spraying.
Oil sprays kill all stages of scales that are present at the time of application and will smother and offer control when applied. Read and follow label directions for application. Because not all chemicals and sprays are available in all areas, it is best to contact your local Dept. of Agriculture Extension Agent to learn what is available in your area for your specific problem.
An alternative to oil sprays are contact insecticides applied during the growing season when the crawler stages of the scales are present. The presence of crawlers can sometimes be determined by sharply tapping an infested twig or branch over a white paper. Crawlers are often orange, brown or purple and appear as moving specks of dust. Because of their waxy protective covering, contact insecticides do not readily control other stages of scales. Contact insecticide sprays will not reach crawlers that have settled under old scales. Contact your local Agricultural Agent for control on outdoor issues in your area.
Q. I live in Arizona where the last few weeks we have had a lot of rain. The problem that I am having is there is standing water under my cottonwood trees. The ground is not draining the water fast enough. Now, I have what looks like a green, murky swamp in a few areas of my yard, not to mention the gnats! I think they are gnats, they are little tiny flying bugs that seem to hatch in the water. Even though it still may be too cold outside I am concerned about mosquitoes. We have had extremely strange weather where one week its cold and rainy, and the next its in the 80's already. What can I add to the standing water to keep the gnats and mosquitoes from hatching in it?
A. Standing water kills trees. The affected area should be trenched to drain water away and the low spots should be filled. Be careful not to let the fill dirt touch the trunks of your trees because it will cause bark to decay and tree to die. There are non-toxic larvicides that can be applied to standing water during breeding seasons, which begins with the onset of warm weather. Because not all products are available in all areas, check with your Dept. of Agriculture Extension Agent for what is recommended in your area.
Bti (Bacillus thuringiensis israelensis) is a naturally occurring bacterium, which acts as a toxin to immature mosquitoes. Bti targets mosquito larvae and has not been found to be harmful to creatures that may be sharing the environment. Altosid is an IGR. Insect Growth Regulators prevent larvae from maturing and is not harmful to other creatures. Antique Oil is non-toxic oil that is sprayed on the surface of water where larvae are present. The oil breaks the surface tension of the water, which prevents the larvae from attaching themselves, and breathing the air, they need to grow and survive.
Q. Can grasshoppers do any good? From what I see, all they do is eat and kill things. Do you think that the organic insect spray will work on them?
A. Grasshoppers breed and grow in dry, pastures, empty lots and roadsides where vegetation is not mowed. When they run out of plants to eat and the weeds dry up, they will move into your lawn and garden. Keeping weeds cut adjacent to lawn and garden and applying control will minimize invasion and reinvasion, but leave a barrier strip of weeds, which you keep watered to give them something to feed on other than your lawn. Treating only the lawn for grasshoppers does not prevent reinvasion. Grasshopper controls are best applied when they are still in the nymph stage and before they enter the lawn from adjacent weeded areas.
Because not all chemical controls are available in all areas, call your local Dept. of Agriculture Extension Agent for recommended chemicals where you live. A residual, oil based insecticide spray tends to be most effective. For organic gardeners, Pepper Wax Spray or Neem Oil are a couple of recommended sprays for insect control. Always read and follow label directions carefully. Repeat applications will be required once grasshoppers move into your lawn. Grasshoppers tend to increase throughout the summer. Some years, there tends to be an outbreak because they tend to run in cycles. Grasshoppers can destroy farmers' crops. A late spring freeze can interrupt their cycle. Grasshoppers do well because they are part of the food chain. Many birds and animals feed on them.
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