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How do I keep lady bugs out of my house? Also, how do I keep out Asian Beetles?
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How can I control the insects that congregate outside my home?
Answer by Diane Alston, Utah State University Extension Entomology Specialist
On warm autumn and winter days, several species of insects can become quite a nuisance as they congregate on south-facing exterior walls of buildings. In addition to being a nuisance outside, they can also become a nuisance inside as they enter buildings to seek shelter. Of these insects, boxelder bugs (a scentless plant bug), are the most numerous. Leaf-footed bugs and ladybird beetles can also be found seeking warmth and shelter on buildings. Adults become active on warm days and emerge from hiding places, returning to shelter as temperatures drop at the end of the day.
Boxelder bugs are about one-half inch long and are easy to recognize because of their distinct coloration — dark gray to black background with red markings on their wings and a red body underneath. Immature boxelder bugs are smaller and bright red with black legs. Leaf-footed bugs are larger, one to one-and-one-half inches long, with a brown body and leaf-shaped “wings” on their hind legs. Leaf-footed bugs can give off an unpleasant odor when handled.
The suggested methods to reduce insect populations are through cultural practices, exclusion, mechanical removal and insecticides. Consider these tips for control.
* Boxelder bugs primarily live and feed on female boxelder trees (a species of maple). They also feed on other maple trees, ash trees, fruit trees, grape and strawberry plants. They primarily feed on the developing seeds. Removal of female boxelder trees that produce winged seedpods can reduce boxelder bug populations if there are not other nearby trees and sources of bugs. Along riparian areas, tree removal is unlikely to yield results since boxelder trees are so numerous. The value of the tree must also be considered and may not justify the anticipated reductions in insect numbers. Insecticides can be applied to boxelder trees during the summer when the bugs are young, but if other sources are nearby, desired results may not be achieved. Carbaryl (Sevin) and other insecticides registered for ornamental trees can be applied to the trunk and limbs to kill young boxelder bugs. Leaf-footed bugs feed on a wide range of trees, shrubs, vines and some herbaceous plants. Removal of host plants is impractical for control of leaf-footed bugs.
* Exclusion of insects and mechanical removal are effective non-chemical control methods. Caulk and seal cracks in foundations and around windows, doors and utility conduits. Remove insects with a broom or vacuum in places they congregate and after they enter buildings. Wash them from surfaces with a stiff spray of water from a hose-end nozzle and sweep them up. Applying insecticidal soap or a homemade solution of mild hand dishwashing soap, such as IvoryÒ, mixed in water (5-10 drops per gallon of water) can deter the insects. Always test a soap solution on a small area before applying it to a large area. Soaps can stain certain materials and even etch glass if the wrong type is used.
* There are many insecticides registered in Utah for boxelder bugs and other nuisance insects. Common active ingredients include carbaryl, cyfluthrin, cypermethrin, lambda-cyhalothrin, permethrin and pyrethrins. As with soaps, always test on a small area first to avoid staining or damaging finished surfaces. Most insecticides applied to exterior surfaces tend to have short residuals because they are rapidly degraded in sunlight and weather. Adult insects also tend to be tolerant of insecticides because of their thick exoskeletons and their ability to disperse quickly and avoid contact with insecticide sprays.
* Generally, the most successful management of boxelder bugs and other insects congregating on outside surfaces is achieved by a combination of the above control and exclusion methods and increasing the tolerance level to their presence. The number of days when large numbers congregate is usually brief, and they soon will disperse to their native vegetation. Visit the Utah State University Extension “Insects and their Relatives” Web site for more information on boxelder bugs and other insects: http://extension.usu.edu/insects/.
Direct column topics to Julene Reese, Utah State University Extension writer, Logan, UT 84322-4900, 435-760-9302; firstname.lastname@example.org
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