Attack of the Box Elder Bugs!
Created on 11/3/2009
It’s a few days past Halloween, but talking to people about box elder bugs (Boisea trivattatus) reminds me of a horror movie. When the weather starts cooling down in the fall, peoples’ homes are sometimes inundated with masses of red and black bugs that freak out many homeowners, especially since it seems you get rid of one batch and another group follows. Kind of like buggy zombies.
Thankfully, box elder bugs are fairly innocuous except for making a mess on and in homes with their excrement. They don’t bite, and are just looking for a warm, dry place to hunker down for the winter. But they do poo as the travel, and if there are enough of them, it’s best to clean up the areas where they’ve congregated.
Their lifecycle is fairly simple. The adults that plaster themselves all over the exterior walls of houses usually find nooks and crannies in which to hide until warm weather coaxes them out of their winter beds. In the spring, they prefer to gather and feed on the female (seed bearing) box elder trees. They’re rarely found on the male trees, but will sometimes go to maple or ash trees if box elders are scarce.
In the late spring to early summer, the female box elder bugs lay eggs in the cracks and crevices in the trunk and branches of the box elder tree. In a few days, the nymphs emerge, and have a ready source of food. Depending on the length of the season, these young of the year can lay eggs themselves rearing a second generation in one season.
Box elder bugs really don’t do any harm in the garden, and they’re really not often seen during the summer. It’s usually only when the weather starts to change in the fall that they’re noticed. It typically starts with a few bugs loitering on the southern or western sides of the house, where it’s the warmest, but some years there seems to be a living mat of red and black, particularly when it was a warm spring followed by a hot, dry summer.
The box elder bugs are looking for a chink in the house armor making another good reason to seal up the house for the winter. The best way to keep them out is to carefully inspect any places 1/8 inch or larger where they can squeeze through. Caulk around windows, utility outlets and spigots to prevent them from overwintering in the walls.
Some homes, particularly those with vinyl siding, are open invitations to box elder bugs since it’s practically impossible to seal up the spaces in the siding. Fortunately, most newer homes have a house wrap underneath the siding that will prevent them for finding their way inside, although some people still don’t want to provide a free shelter under the siding. The easiest way to catch them is to vacuum them with a Shop-Vac, or blast them with the hose. It’ll take several days, if not weeks, because they keep coming back, but it’s ultimately effective.
