If you had box elder bugs or multi-colored Asian lady beetles congregating on your house last fall, you’re probably starting to notice them appearing in your house again as the weather warms this spring. Last fall they were able to find a place on/in your house to overwinter and now they are attempting to leave your house to head back into the fields where the beetles, like all ladybugs, will feed on aphids and the box elder bugs will feed on the sap of certain trees.
If you’re having a problem with them in your house you can manually remove and release them outside, you could vacuum them up although be sure to empty your vacuum when you’re done, or some folks prefer to bug bomb their house. If you use a fumigant pesticide inside your house, it will not kill any bugs that are still inside the walls. Vacuuming and capture/release will have to be done repeatedly until they have all emerged from the walls, attics, or from under siding. Do not squish them if possible as they can stain whatever you squish them on.
The key to not having them emerging into your home in the spring, is to keep them out in the fall when they are seeking overwintering sites. Various tactics, including sealing your home more tightly, and using insecticide sprays on the exterior of your house, can help. Exterior sprays generally should be done in late September or the first week of October. For more information on control options check out UW Extension’s multi-colored lady beetle publication.
Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@Wisconsin.gov), 920-662-5172.