Why Do I Get Lady Bugs in My House?

The multicolored Asian lady beetle (Harmonia axyridis), also known as the ladybug, enjoys hanging out in your house. These beneficial garden insects begin setting up shop in the fall and have taken their shoes off and gotten comfortable by the time the full onslaught of winter arrives. The reasons Asian lady beetles make their way into your home vary, but it all begins with instinct. Simple methods exist for managing the influx of lady buys into the home.

Simply put, you get ladybugs in your house because of instinct. As summer fades to fall, ladybugs instinctively leave their feeding grounds in search of warm, protected places to spend the winter. In their native environment in Asia, ladybugs winter in crevices on cliffs. Because ladybugs in the United States feed on garden and woodland insects, the closest structure for them to spend the winter in usually ends up being the house of the gardener on whose pests the bugs feed. Periods of heaviest migration from feeding grounds to the home occur on sunny days following periods of cool weather. When springtime temperatures reach the mid-60s, ladybugs leave the house and return to their feeding grounds.

Studies indicate that ladybugs are attracted to light. Reflective surfaces and buildings with alternating light-dark color motifs prove most likely to attract Asian lady beetles. Sources further show that ladybugs generally head for the largest structure in a given area exhibiting attractive characteristics. In short, if you live in a giant, shiny house with a black and white exterior set against an aphid-infested woodland, make room for some winter guests.

Ladybugs enter houses through small cracks, particularly those at the juncture of two surfaces such as a wall and a floor or a window and a wall. Beetles sometimes winter in these cracks, though more commonly continue through cracks en masse and congregate in places such as attics, wall cavities, crawl spaces and other protected areas. As the weather warms and beetles prepare for their return to the feeding sites, ladybugs become active. They leave their sheltered, protected spaces and sometimes invade areas such as living rooms and kitchens. Ladybugs exhibit no damaging behavior; they do not bore or chew surfaces and do not lay eggs in homes. They won’t eat human food and carry no diseases.

The simplest and most effect method of controlling Asian ladybug infestation entails plugging all the crevices and cracks on the surface of a home large enough for beetles to enter through, including slight apertures where phone lines and pipes enter the home. Caulk is the ideal substance for such projects. Repairing broken screen doors and windows increases protection from ladybug invasion as well. Commercially available traps use pheromones or light to trap ladybugs in removable bags so that homeowner can transport the insects elsewhere as a means of prevention. University of Kentucky entomologists warn against the use of bug bombs and other chemical deterrents as such poisons may prove harmful to humans and pets but generally exhibit little effect on ladybugs.