What's Black and Red and Really Stinks? 

You see them crawling all over your patio furniture. You see them congregating at the base of a tree. You find them crawling across the kitchen floor. If you step on them, they leave a telltale odor, and purplish stain on the floor. What are these ominous creatures that seem to be everywhere? Well, if they are about 1/2" long, have a black body, and three red lines crossing their back, then, they are Boxelder bugs. 

What are Boxelder Bugs? 

Boxelder bugs are more of a nuisance than a damaging insect in terms of tree maintenance and lawn care. They feed on many different plants, but their favorite source of food is the seedpods of the female Boxelder tree. They will feed on the sap of maples, ash, and other shade trees, but do not cause significant damage. 

Boxelder Bug Seasonal Populations & Habitats 

They become a nuisance in the late summer and early fall when they congregate on the south sides of buildings, rocks, or trees. The bugs are in the process of locating a hiding place for the winter. During this random search, they often end up inside of houses. They will gain entry through cracks in the foundation or siding, gaps along the windows, or any other small openings they find. 

Preventing Boxelder Bugs 

Prevention seems to be the best defense against these annoying insects. If you have had a problem with Boxelder bugs in the past, now would be a good time to plug up the holes, and caulk any cracks. If they do get inside, most of the normal, ready-to-use home insect sprays may not kill them. It is best to use a vacuum to 'clean' them up. Outside, a soap solution of 5 tablespoons of liquid detergent in one gallon of water will effectively control them. You may need to spray a couple of times over several days if they are a major problem. You can spray a household insect control at the foundation to aid in prevention of their entry into the house. Be sure to read and follow all label directions before using any pest control product. When in doubt, contact your neighborhood Spring Green professional lawn care service. 

More Than You Really Want To Know Department Boxelder Bug Control - North Dakota State University Extension Service