Boxelder bugs (Bosia spp.) Are basically harmless insects that don’t bite, damage property, injure plants or carry diseases, but they can nevertheless become a nuisance because of their sheer numbers. They multiply quickly in home landscapes, and you may spot up to 1,000 bugs sunning themselves on tree bark, walls or your home’s base. Conventional insecticides don’t work very well on boxelder bugs, but it is possible to take a few steps to get rid of the bugs without using harsh chemicals.
About Boxelder Bugs
Western boxelder bugs (Bosia rubrolineata), the species most commonly seen in the western areas of the U.S., are beetle-like insects with dark gray to black bodies that reach about 1/2-inch long and 1/3-inch wide. They sport three distinctive red lines behind their heads and red veins in their wings. The bugs earned their name because they primarily feed on the seedpods, flowers and leaves of feminine box elder trees (Acer negundo), which develop in U.S. Department of Agriculture plant hardiness zones 5 through 8. Their hunt for hot overwintering sites often brings the bugs inside. Those that remain outside typically hibernate beneath garden debris. When warm weather arrives in spring, the bugs emerge to begin feeding and mating. Adult females find a feminine box elder host tree and lay clusters of several hundred small, red eggs on the leaves and in bark crevices. They also lay egg clusters on fallen box elder seedpods. The eggs hatch between 10 and 19 days after, and the nymphs remain on the ground to feed on fallen seeds.
Boxelder bugs are easy to drown, notes that the UC Statewide IPM website. If the sight of numerous bugs converging on tree trunks or the exterior of your home grosses you out, then wash them away with a powerful stream of water from a garden hose. Using a shop vac physically eliminates boxelder bugs, but put the vacuum contents in a sealed trash bag therefore surviving pests don’t escape. Should you use a wet-dry store vac, adding a few drops of liquid dish soap and water to the cylinder will drown the pests without them releasing their foul odor. Whether rinsing or vacuuming, start looking for boxelder bug swarms on the western and eastern sides of trunks and hard surfaces, which is where the bugs want to gather on sunny autumn days.
Youthful boxelder nymphs frequently feed on box elder seeds that fell the previous autumn. Raking up and discarding fallen seedpods helps reduce pest populations by removing food sources. Boxelder bugs hide out and overwinter in batches of stone, leaves, wood, grass and other garden debris. Removing those piles eliminates hiding places and exposes the remaining bugs into the environment. Keeping a 6- to 10-foot-wide bud- and grass-free area around the base of your home helps keep the pests from entering your residence.
Spray With Soap
Employing an easy, homemade soap solution can lessen boxelder bug numbers without discharging potentially toxic chemicals to the environment. Mix 5 tablespoons of liquid laundry soap or 1/2 cup dry laundry detergent with 1 gallon of water. Use a spray bottle or small garden sprayer to thoroughly cover affected surfaces. This protected pest control alternative leaves no unpleasant deposits behind, but you’ll need to spray around every 3 days because the soap just kills bugs on contact. Avoid getting the solution on vegetable or ornamental plants as the soap may injure the leaf. Prior to using soap, test the solution on a small, inconspicuous area to make sure it wo not stain the material. Although nontoxic, reduce the risk of skin and eye irritation by wearing waterproof gloves as well as protective eye wear and clothing when mixing and spraying a soap solution.
Prevent Future Infestations
Removing female box elder trees may discourage boxelder bugs from staying in your yard, but the highly portable bugs may fly in from several blocks away. More often than not, the ornamental value of this tree far outweighs the temporary relief you’ll receive from removing the plant. Avoid planting feminine box elder trees in your yard if you’ve had previous issues, however. Cease bugs from entering your home by weather-stripping or caulking around windows, doors and foundations. Repair tears in window and door screens and cover ports with a fine-mesh viewing. Perform these chores in the summer or early autumn before the bugs begin searching for overwintering sites. If any boxelder bugs nevertheless manage to invade your home, suck them up with a vacuum cleaner and remove the contents in a covered trashcan.