Asian lady beetles closely resemble native ladybugs in appearance, but Asian lady beetles are one of the few ladybug species in the US that hail from southeastern Asia. These beetles vary greatly in size and color, as they are generally around ¼ of an inch long, but specimens at higher elevations are noticeably larger. Some specimens have dull red wings, bright red wings, while others have beige wings.
In response to the arrival of cooler weather during the fall season, Asian lady beetles seek overwintering sites on the sunny side of houses and buildings. They use chemical cues to determine which crevice makes for the most ideal overwintering site. These chemical cues have not been identified, but experts believe that they may come from feces leftover from previous overwintering beetles. This would explain why the beetles typically choose the same overwintering sites year-after-year.
From exterior cracks and crevices on walls, Asian lady beetles make their way into the interior living spaces of houses, but others simply fly straight into homes through open doorways, windows and crawl spaces. Some enter homes through defective weather stripping on exterior walls, or even through soffits and vents that lead into attics. Within homes, massive numbers of Asian lady beetles emerge from light fixtures, vents, ducts, and most overwinter within wall voids, but luckily, they are unable to reproduce indoors. They may remain indoors for the duration of the winter, and emerge in large numbers once again during the spring season in an effort to fly outdoors.
Luckily, Asian lady beetles are mainly a nuisance, but they are known for inflicting bites, and crushing them releases a bodily fluid that stains clothing, furniture upholstery and carpeting. Asian lady beetles may reduce the quality of indoor air, and their indoor presence has been associated with asthma attacks and skin rashes. Installing mesh screens on attic vents and crawl space openings, placing door sweeps to block door gaps, and using caulk to fill holes and other entry points on the exterior walls of a home will go a long way toward keeping Asian lady beetles from invading a home.
Have you ever experienced allergy symptoms in response to Asian lady beetle invasions into your home?