Are you being inundated with boxelder bugs? Fortunately they are harmless, not disease bearing, they do not damage the house, its furnishings or occupants but they are definitely a nuisance and can be difficult to control!
According to our Iowa State University Entomologists during the summer months, they live, feed and reproduce on trees, shrubs and other plants. They are not restricted to box elder trees as is commonly assumed, but will also be found on other trees, most commonly maples. They feed on the sap from the host plant but do not cause significant damage to the plant. They become nuisance pests in the fall when they leave the plant to find hiding places for the winter. During their search for warmth they congregate on the south sides of buildings, trees and rocks. From there they stray into houses through cracks in the foundation and siding, gaps along windows and doors and other small openings. There they remain inactive while it is cold until they are warmed by the heat from a furnace or the sun and they crawl out into the rooms.
The best deterrent is to prevent their entry into your house by caulking and sealing possible entry sites. Spraying with a lawn and garden insecticide (suggestions include Sevin, Diazinon or Orthene) or soapy water spray (5 tablespoons of liquid detergent per gallon of water) outside on the masses of bugs perched on and along the foundation in the fall can give some relief. Repeated applications are usually necessary when using a soapy water spray. Professional pest control operators can also be used for exterior treatment in the fall.
Once the boxelder bugs are in your house they are generally not killed by the “flying insect” aerosol household insecticide products. The residual insecticides such as “ant and roach killers” also have not been shown to be of much benefit. A sure control for bugs already in the house is to remove them as they appear by vacuuming, sweeping or picking them up and discarding.
For more information on insecticides available to homeowners please see “Insecticides in the Home Landscape and Garden” .