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How insects find way into your Michigan home for winter months

Have you ever wondered how insects break into your home for the cold months?

You've locked the doors, shut the windows, set your home alarm -- but they're still getting in! What's the deal?

Related: Michigan house centipedes: Why you shouldn't kill them

Howard Russell from MSU Extension says it's probably not what you think:

Many people who offer advice on reducing these unwelcomed guests suggest sealing exterior cracks and holes with caulking to prevent their entry inside. This may work on older homes with clapboard siding, but no amount of caulk is going to keep them out of a home with vinyl siding. Vinyl siding and soffits are not tightly nailed down; these are nailed loosely or as they say in the trade, "hung." It is done this way to allow these vinyl panels to expand and contract with changing temperatures.

Fall invading insects can find their way around the edges of these loose panels and into wall voids and attics. If homes were not heated these bugs would likely be content to go dormant and spend the winter in these cozy confines.

Unfortunately, our homes are heated and this warmth keeps these bugs active and as such, they find their way into the living space probably around baseboards, window and door moldings, openings for electrical outlets and fixtures, openings for heating/cooling vents and other such pathways. There is very little that can be done once the bugs are inside the walls. In homes invaded by these bugs, it is very common and likely that one will continue to see them throughout the winter.

Even aggressive and costly insecticide applications may not be effective because it is nearly impossible to treat every hidden area that may be harboring insects. Sealing cracks around electrical outlet boxes, switches and light fixtures, and around window and baseboard molding on the inside walls will help keep the bugs trapped within the walls. In older homes with double-hung windows equipped with pulleys, insects commonly enter living areas through the pulley opening.

Masking tape applied over the opening will keep insects from entering through this route. A vacuum cleaner is a pretty effective method of removing the sluggish, slow moving bugs from inside the house. Spraying the outside walls of homes, especially the south and west facing walls with a long lasting insecticide registered for this use in September can help reduce the number of insects entering homes. These sprays should be applied when the first bugs are noticed congregating on outside walls.

Before treating the whole house, spray a small test area to make sure the insecticide does not stain the siding or paint. Be sure to read and follow all directions on the pesticide label. Spraying the outsides of homes will, no doubt, involve spraying above one's head so be sure to wear protective clothing such as a wide-brimmed hat and raincoat. Eye protection is a must.

The bugs that we are most likely to see on our homes this fall include the multicolored Asian lady beetle, cluster flies, western conifer seed bugs, foreign grain beetles and everyone's favorite: the boxelder bug.

Howard Russell notes that in general, these bugs are harmless: most do not bite; they do not eat fabrics, stored foods, wood or pets; and they do not lay eggs in the house.