Why lady beetles enter your house in winter and how to keep them out

In Extension Daily, Alabama Cooperative Extension News

by Sarah Buck, Alabama Cooperative Extension Service

When temperatures begin to drop, the multicolored Asian lady beetle makes a move. Believe it or not, it wants to come inside your home. These orange and black ladybugs are notorious for congregating on the sides of buildings during fall months and moving indoors when given the opportunity. Awareness of the multicolored Asian lady beetle and understanding why it invades homes  is key to preventing an infestation before it begins.

As one of the world’s most invasive insects, the Asian lady beetle ( Harmonia azyridis) is often seen as a pest because of its tendency to enter homes, have an unpleasant odor and leave stains on fabrics or walls. Although the beetle can be a pest, it also serves a valuable role in the environment.

“The presence of lady beetles has both direct and indirect beneficial impacts on the environment,” Dr. Xing Ping Hu, specialist with the Alabama Cooperative Extension System, said. “They reduce or even eliminate insecticide use against certain pest insects. This reduces toxic contamination to water, soil and air, and increases health and safety for people, wild animals and the environment. This, in turn, reduces the cost of pest control and increases harvests.”

Hu explained that the multicolored lady beetle is native to Asia and was imported for use as a biological control agent for crop-destroying insects in the United States. It is characterized by a black M marker on its cream-yellow head.

“Biological control agents are natural enemies of pests,” Hu, who is also a professor of entomology at Auburn University, said. “The Asian lady beetle was originally introduced to the United States because there was no efficient, native, natural enemy to control certain agricultural aphids. The beetle’s natural control of aphids in pecan orchards and some ornamental plants has decreased insecticide usage against those pests.”

But why do these insects enter homes and what do they do?

According to Hu, in its native country, this beetle hibernates in caves, cracks and crevices during the winter. In the United States, these insects use buildings to protect themselves from winter weather and to retain the heat emitting from them.

“The greatest damage caused by Asian lady beetle is the discomfort they give to residents,” Hu said. “It is common for thousands of beetles to congregate in attics, ceilings and wall voids. At warm hours, they may enter into house living areas. Additionally, they release a yellow fluid as a defensive chemical when being handled or squashed. The yellow fluid has an unpleasant odor, and can not only stain walls and fabrics, but also cause mild skin related allergic reactions in some people.”

Prevention is the key to controlling the Asian lady beetle’s ability to enter the home

“Before Asian lady beetles seek overwintering sites in late fall, homeowners should caulk and seal exterior cracks and crevices around door and window frames, and cable and pipe openings,” Hu said. “Lady beetles are typically attracted to light and lighter colors. So, don’t turn on outside wall and door lights at night during the time when they are seeking overwinter sites.”

If the beetles do find a way to get indoors, Hu recommends using a vacuum to remove them.

“Chemical application is not typically recommended, unless the infestation is very heavy. In this case, professional pest control advice should be sought. The best approach is prevention. Don’t let them become a household nuisance in the fall and winter.”

Hu encourages homeowners to use the catch and release practice since the Asian lady beetle can be beneficial to gardens and backyard plants.

The good news about lady beetles is that they are not poisonous or harmful to humans, just unpleasant to have around or inside the house.

According to Hu, “The comforting thing about Asian lady beetles is that they don’t damage homes, chew or bore holes in walls or eat carpet or furniture. This makes the Asian lady beetle a mixed blessing.”

More Resources:

The Multicolored Asian Lady Beetle

Management of Pest Insects In and Around the Home

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