When I was growing up near Cosgrove, west of Iowa City, I would go to my neighbor’s house after school. Mid Davin was an older lady who made noodles and cookies. I would get her mail on my way past the box and come visit with Mid for the afternoon. I remember watching a lot of Jeopardy and other afternoon game shows. When the news came on, I went back to my house and did my homework. I figured out years later that my Mom and Mid’s kids had probably created this arrangement to provide Mid with some company each day and to help keep me from killing my sister and brother. One of the things I got out of it, other than some great memories of the cookie and fresh noodle smells, was how messy boxelder bugs are.
Mid didn’t complain too much about them getting in the house, but she hated all the spots they left on her windows. I don’t think I ever helped her clean the windows because she always got to them before I got out of school!
Boxelder bugs are pretty common in Iowa and are most abundant after summers where May is very warm and July is very dry. I don’t think we have to worry about that this year. However, there can still be problems even in years when a widespread “outbreak” of Boxelder bugs doesn’t occur.
Most of the warm parts of the year you probably won’t see too many. I have seen a few on my flowers and bushes in the garden, but they haven’t “attacked” the house yet. They live, feed and reporduce on trees, shrubs and other plants which include boxelders (surprise, surprise), maples and ashes.
Boxelder bugs feed on the sap from the host plants but don’t cause any significant damage. They become a nuisance in the fall when they leave their plant homes to find a warm spot for the winter. You will know when this happens when you see them congregating on the warm side of the houses… and on the windows leaving spots from their feet!
They move through cracks in the foundation and siding, gaps along the windows and doors and other small openings. While in the walls or attics they are inactive as long as they are cold. If they get warmed by heat from the furnace or the sun they become active during the winter and that’s when they crawl into the rooms where you can see them. And probably leave spots on your walls.
There is no good way to figure out when and where a problem will be until it starts. By then it is probably too late for treatment. Boxelder bugs can be controlled on the trees in the mid summer with insecticides (labeled for boxelder bug control) but it will probably not work well. Spraying large trees is difficult and is usually impractical.
Same as with the Asian Lady Beetle, the best way to keep Boxelder bugs out of your house is to seal all possible entry sites. You can spray to reduce the number outside to limit the number that will get inside. You can use a lawn and garden insecticide or soapy water spray (which is 5 Tablespoons of liquid detergent to a gallon of water) on masses of bugs on and along the foundation in the fall. You may have to repeat the applications especially when you use the soapy water spray.
There is no easy way to get rid of Boxelder bugs that are already inside the house. they are usually not killed by the household aerosol inseciticides and most are not of much benefit. The best way to control bugs already in the house to is vacuum, sweep or pick them up and discard them. Sounds familiar!
So far they haven’t made it into our house yet, but I’ll have to keep an eye on the windows and make sure the boxelder doesn’t mess them up!