"Wasps, hornets, yellow jackets and other social insects abandon their nests in the fall and often move into nearby homes," said Beverly Sparks, an entomologist with the UGA College of Agricultural and Environmental Sciences. "They're just seeking shelter from the cold."
Insects are cold-blooded. They can't produce their own heat, so they rely on their environment to keep their body temperature regulated. When it gets cold, they look for warmth.
Often, they find that vital warmth in attics, garages or other protected areas around homes and heated buildings.
Sparks said entire colonies of wasps, hornets and yellow jackets, except the fertilized females, die during the first cold spell of fall.
The fertilized females are the queens of the colonies. Their job is to lay eggs. All the workers, males and unfertile females die. Only the queens overwinter.
Social insects usually build nests for their colonies and protect the nests, and the young insects they contain, aggressively. They're usually most aggressive during fall, Sparks said. As food becomes scarce, the insects fight harder to get and protect it.
But after most of the colony dies, the remaining queens are less hostile.
"They're not trying to protect their nests anymore, so they're much less aggressive," Sparks said. "And social insects usually don't build new nests until the spring, so they probably won't sting anyone in the house where they move in."
The easiest way to remove any wasps, hornets or yellow jackets you find is with a vacuum cleaner. Pyrethroid-based sprays will knock down and kill flying insects quickly. But most insects you'll find in the house are moving pretty slowly. "They'll be easy to get with the vacuum," Sparks said.
But Sparks said not to kill all the insects that move in for the winter. Ladybugs move indoors, too, to stay warm. Ladybugs eat many damaging insects both in gardens and on farms. They're on the gardeners' and farmers' side in the constant insect war.
"You really don't want to kill ladybugs," Sparks said. "Just sweep them up and release them outdoors."
If you don't want to run an insect hotel, she said, it's easy to keep them from checking in. "Use a caulk gun to fill cracks and holes they can fly or crawl into," she said.
If the insects are already inside, they'll move out again in the spring. "They're just trying to stay warm and survive the winter," Sparks said.