Boxelder bugs are about half an inch long, colored black or dark brown, with three red-orange stripes on their thorax and red-orange borders of their wings. They resemble beetles, but are actually a type of insect known as “true bugs”. True bugs don’t chew like beetles do; their mouthparts are designed to pierce and suck.
Boxelder bugs pierce the plant with their proboscis and suck out the sap. Early in the year when they are coming out from their winter shelters, they eat from whatever plants are available. Once it warms more, they are usually found in a variety of maple called the box elder tree (the source of their name) but are also sometimes found in other varieties of maple and ash. Since their favorite food is the seeds of the boxelder, they are most often found on female boxelder trees. They are not considered agricultural pests; the only time they will do any damage to fruit trees and plants are in unusually dry years when their favored boxelder trees are not able to provide enough food, and they seek out fruit for nourishment.
You are most likely to notice them when the weather changes. In the fall, they start looking for cozy places to spend the winter. They ought to hide under loose bark or wedged into sheltered areas near their trees; unfortunately, human habitation provides many warm, sheltered areas that are more attractive than loose bark. They will crawl through any small cracks in the house or around doors or windows, and suddenly, you have hundreds of black bugs seeking shelter in your walls, basement, outbuildings, or garage. Once it gets solidly cold, they will become inactive and hibernate and you might not notice them again until spring.
Don’t breathe a sigh of relief yet, though; when the days start to warm again, you will notice the newly-awakened bugs emerging. If they are weathering inside your house, this might not even wait until spring – the central heating might wake them up and you notice them emerging into your home as they wake up and follow the warmth searching for food. When this food is not found in the house, they die and leave drifts of dead bodies around the house.
The most effective way to deal with a boxelder infestation is to prevent it. Make sure your home doesn’t have easy access to the boxelder bugs. Make sure your windows and doors are sealed and your screens are in good shape. Don’t leave windows or doors standing open. Check your house over for cracks that might allow entry. Caulk the places where materials meet, such as stone to wood, or where utilities such as cable wires or dryer vents enter or leave the house. For necessary ventilation, be sure that the holes have a proper ventilation cap or screen. (Fixing all these things will also help your house be more weather-tight and efficient.)
If you’ve noticed boxelder bugs have started to congregate on your house, you can try spraying with them with a soap and water mixture (rumored to kill them if sprayed directly on the gathered bugs) every single time you see them, or vacuum them up with a shop vac, but a more effective solution would be to contact Miller Pest & Termite. We have ways to kill the boxelder bugs and to make your house unattractive to the bugs, protecting you from an invasion.