Box-elder beetles taking up residence, what to do about that
Back when stink bugs (Halyomorpha halys) were first found in Pennsylvania and I heard the horror stories of home invasions, I steeled myself mentally for the inevitable in our own house.
Thankfully, an invasion never happened and I’ve been relieved, year after year, to never see more than a handful of the dreaded bugs in the house in any season.
It’s been a surprise then, to be a bit overrun with box elder beetles this winter.
No matter how many we pick up and toss outside, there are still more that we come across nonchalantly roaming the floors and walls, or that suddenly appear walking on one of us, coming seemingly out of nowhere.
I had previously noticed these bugs in large quantities in the mulched area under the big silver maple tree in our yard but never thought much about them other than to admire their distinctive, geometric, red-andblack pattern.
There are no box elder trees on our property or anywhere else in the neighborhood as far as I know, but box elder (Acer negundo) is a member of the maple (Acer) genus and the bugs will hang out around them as well.
Within reason, I’m OK with insects, although we have a very one-sided agreement: insects have the whole outdoors to inhabit; once they cross the threshold into our space, all bets are off.
Having said that, while it’s certainly startling to have one of these bugs land on us or seem to want to share our dinner, they are pretty benign. They don’t sting or bite, nor do they infest the food in the pantry.
So, what are these insects doing in the house in the first place? Like stink bugs, box elder beetles seek a sheltered spot to overwinter, for instance under tree bark. But they’re just as happy — possibly happier — to take up lodging in a nice, dry, warm house.
What can you do to keep them out?
Exterminators offer the following tips but point out that preventing incursions of box elder bugs requires an exceptional job in finding and sealing every possible entry point.
• Trim trees, especially box elder trees, away from the exterior of your home.
• Seal cracks in the foundation and exterior walls of your home.
• Fill in spaces around wires, pipes, and utilities entering your home from its exterior.
• Repair holes found along your roofline and at roof intersections.
• Put mesh covers over vents leading into your home.
• Place tight-fitting caps on all chimneys.
• Place weather stripping around all exterior windows and doors.
(Info from M.A.D. Exterminators in Norristown, http://tinyurl.com/3zn4e7ms0)
Somewhat surprisingly for a species that can be invasive, box elder beetles are native to North America.
Their current range is the eastern United States, southern Canada, Mexico, and south into Guatemala. Why are we seeing a bumper crop of them this year? Experts say that it’s probably due to the relatively dry summer we had in 2023, providing optimal conditions for breeding.
These bugs do not breed indoors, so you don’t have to worry about increasing numbers of them. And once winter is over, they’ll go back outdoors without you having to do anything.