Fall is a popular time of year for beetles to start moving indoors in an attempt to escape the increasingly cooler weather. The colder nighttime temperatures will cause some species of beetles to hang out on the outside of the south- and west-facing walls of your house during the day before making the move indoors. Many beetles looking to seek shelter in your house are harmless, but they can be a nuisance. Preparing your house for an insect invasion each fall and ongoing prevention may help in limiting the number of beetles breaching the exterior of your house.
Caulk exterior cracks and holes. Caulking has its limitations on how effective it will be in keeping beetles out of the house, depending on type of siding on the house. Insects can find their way around the edges of loose vinyl siding and into walls and attics, according to Howard Russell of the Michigan State University Diagnostic Services department. Other outdoor areas to focus on caulking are around windows, doors, openings for utilities and heating and cooling vents.
Remove rocks, boards and other objects from the exterior base of the house. Some beetles hide under rocks and boards around the outside walls, and taking the items away can discourage beetles from gathering near the house, according to Darryl P. Sanders of the Department of Entomology at the University of Missouri.
Spray exterior walls with a long-lasting insecticide in September when the beetles first appear. Focus insecticide application on the south and west walls. Make sure to apply the insecticide on a test area to ensure it doesn't stain siding or paint. For problems with ground beetles, spray an appropriate insecticide 2 to 3 feet from the ground up and treat a band around the house from the foundation out about 5 to 10 feet, according to Sanders. With any chemical application, follow all of the directions on the label. Wear protective clothing, such as a raincoat and wide-brimmed hat, and eye protection.
Seal interior cracks and gaps. Focus on areas around electrical outlet boxes, switches and light fixtures. In older homes with double-hung windows and pulley system, putting masking tape on the pulley opening to keep beetles out of the house.
Inspect window and door screens. Check the window and doors screens for a snug fit and rips in need of repairing. Focus on basement windows and entries.