Expert Advice: Pesky Box Elder Bugs

Q: Box elder beetles are like locusts on our property. They cover the grounds and houses, and they’re getting into homes. We have two huge 40-year-old box elder trees. Help us get rid of them! — Kathy Johnson, Sebastopol, CA

A: During spring and early summer, box elder bugs generally mind their own business. In late summer and fall, after they’ve mated and laid eggs, the bugs start looking for a cozy place to spend the winter. At this point they can become a real nuisance, congregating around vents, windows and doors. Bugs that manage to find their way inside overwinter in walls and attics and then move back outdoors in the spring.

Removing the two box elder trees from your yard may reduce the problem, but it won’t eliminate it because the insects are willing to travel several miles for food and shelter. Box elder bugs are particularly attracted to hot, sunny surfaces, so carefully weatherize these areas to seal off any possible points of entry.

Fortunately, box elder bugs appear in great numbers only about two years out of 10. Next year they probably won’t be much of a problem.

Did you know
Box elder bugs (Boisea trivittata) prefer the seeds of maple species, such as box elder trees (Acer negundo). They rarely eat ornamental plants, and that's good news for gardeners!