Ladybugs, those cute little critters, are just fine to encounter in the great outdoors, but lately they've become pests in many homes as populations have gotten out of control. The Asian ladybug, introduced to North America and Europe to control aphids, burrows into the structures of homes to hibernate over the winter months. They don't cause damage, but can be a nuisance.
Identify what kind of ladybug you have. It is impossible to tell an Asian ladybug from a regular one, but if a swarm appears in your home in October, it is likely Asian ladybugs looking to hibernate for the winter. Carefully squash one (see Warnings below). If it leaves a foul odor, you have an Asian ladybug.
Sweep or vacuum up the little critters as you notice them. Place a nylon in the filter of your vacuum cleaner to catch them so they don't get stuck in the vacuum cleaner itself.
Call the exterminator. For a really big mess, you may want to use insecticides, but most home-use insecticides are not proven effective against Asian ladybugs. If your infestation is big, call a professional exterminator.
Seal off your home. Asian ladybugs get into homes through cracks under doors and near windows. Use caulk to seal cracks in your house to prevent the ladybugs (and other insects) from getting in to hibernate in the first place.
Frightening or killing an Asian Ladybug will trigger a "reflex bleed," which can attract other Asian Ladybugs. Asian Ladybugs can bite, but rarely cause anything more than very slight irritation. Only a very small number of people are allergic.