Box Elder Bugs

Selective

Boxelder bugs feed on low vegetation and seeds on the ground during the spring and early summer. These black and orange bugs move to the female seed-bearing Boxelder trees, starting in mid-July. Eggs are normally laid on the trunk, branches, and leaves of the tree.
There is no noticeable feeding or injury to the trees. During late summer and fall, boxelder bugs begin leaving the trees to find protected areas for the winter. Although many young insects may be present in the fall, only full-grown bugs survive the winter. These adult boxelder bugs are capable of flying several blocks. Some homes are especially attractive to boxelder bugs while neighboring buildings may have few. This usually depends on the amount of southern or sunny exposure a building has.

Sunny

Boxelder bugs like sunny areas and is attracted to buildings with a lot of southern exposure. Buildings standing taller than surrounding structures can also attract large numbers of bugs. Although some people attribute the clustering of boxelder bugs to the color of the building, boxelder bugs are found on buildings of all colors. As the weather cools, these insects will push into cracks and enter houses near foundations. Many crawl under siding or shingles and get into wall voids and attics. They also may enter through doors, windows, vent openings, and other accessible areas. Once indoors, boxelder bugs are nothing more than nuisances.

Boxelder bugs do not bite people and are harmless to property. When extremely abundant, they can stain walls and curtains with their excrement. Occasionally some may seek moisture and may be found around houseplants. They rarely attempt to feed on indoor plants, but if they do, no injury occurs. Indoors, boxelder bugs live just a few days and do not reproduce. During winter, boxelder bugs are generally inactive.

Population Explosion

However, mild, sunny days can wake up boxelder bugs and some may enter the home's interior from their overwintering sites in walls and become a nuisance. Despite the circumstantial evidence, boxelder bugs are not reproducing in homes. The first warm spring days bring the bugs out of their protected wintering places as they prepare to fly away to feed. Unless they are bothersome outdoors, particularly at doorways, there is little point in spraying them. These bugs return to trees for egg laying. Those trapped in basements and houses die during spring.

Boxelder bugs are not a serious problem every year. They become most abundant during hot, dry summers. Recently, they were numerous in 1988, 1987, 1978, 1977, and 1975. They were also abundant in 1958, 1949, and the hot dry years of 1936 and 1935.

Preventing Boxelder Bugs from Coming Indoors

The goal of boxelder bug control is to prevent them from entering indoors. The first step is physical exclusion. Caulk or seal cracks and spaces found around the foundation, siding, windows, doors, and other potential entry points. Screen any vents that don't close properly. If large numbers of boxelder bugs are still found indoors, you may want to supplement your non-chemical efforts with an insecticide treatment around the exterior of your home. Repeat treatments are often necessary, especially when boxelder bugs are numerous.

Boxelder Bug Insecticides

The best time to spray is late summer and fall when boxelder bugs are first clustering around the outside of buildings. When spraying the exterior of buildings use one of the following insecticides: Zamzows Z-One. Z-One is available exclusively Zamzows retail stores. It comes in a ready to use trigger bottle, a 16-ounce concentrate or a 32 ounce ready to spray bottle. Be sure to read and follow all label instructions before using.

A soap mixture can be used as an alternative to synthetic insecticide. Mix approximately 1/2 cup of a laundry detergent in one gallon of water in a hand sprayer or squirt bottle. Test this mixture first on an inconspicuous spot before applying it to the entire area, as it might stain cedar and other siding. Once you determine the mixture to be non-staining, apply a coarse spray directly on the bugs as often as necessary, starting in late summer when boxelder bugs first start congregating around your home. The soap mixture affects only those boxelder bugs that are sprayed. It does not prevent other bugs from returning to the site. Therefore, it is important that the bugs are sprayed as often as they cluster outside the building to maximize control. You may also consider hiring an experienced pest control service to treat your building’s exterior. They have access to effective, residual insecticides, such as Tempo and Demon that give long-lasting control against boxelder bugs.

Large numbers of boxelder bugs may also be seen in the spring on the outside of buildings. These insects are emerging from their over-wintering sites and are flying back to boxelder trees. Spraying boxelder bugs in the spring is not suggested; it has no impact on the number of insects found indoors in the spring or the numbers of bugs found next fall.

Treating Your Home for Boxelder Bugs Indoors

Boxelder bugs found inside should be controlled by physical means, such as with a vacuum cleaner. Insecticides are not normally suggested. Remember that boxelder bugs do not live more than a few days indoors, do not breed inside, and are essentially harmless. If large numbers are present, their numbers can be temporarily reduced with an aerosol ready-to-use insecticide containing either pyrethrins or tetramethrin. These sprays will not prevent more boxelder bugs from returning.
Caution: Read all label directions very carefully before purchasing insecticides and again before using them.

Spraying or Removing Trees for Boxelder Bugs

Spraying or removing the seed-bearing boxelder trees on which the bugs feed often is not a practical solution to the problem; the adult boxelder bugs can fly up to several blocks and boxelder trees are usually common. However, if your residence is fairly well isolated with no other female boxelder trees in the area, you may benefit by spraying or removing those trees on your property. Boxelder bugs do not live on male non-seed bearing boxelder trees.

Keep in mind that boxelder bugs are not common every year. You can identify a boxelder tree by its leaves and its unsymmetrical, ragged appearance. Boxelder seeds are also very characteristic. They are winged seeds, similar to maple seeds. Boxelder seeds appear in small clusters on the tree. Although boxelder trees are often found growing naturally along lakes, streams, and in thickets, they are sometimes found as a landscape tree, they are fast growing, reaching a height of about 30-50 feet.