Ladybird Beetles Begin Home Invasions

Orange and black lady bugs are gathering in large numbers in many areas of Maryland, alarming some residents and causing an inconvenience to many more. Originally from Asia, the multi-colored Asian ladybird beetle is found throughout the eastern United States. The pill-sized beetles invades houses by hundreds or thousands about mid- to-late October each year, looking for a warm, cozy place to spend the winter.

"Unfortunately for homeowners, the beetles find houses attractive," said Maryland Secretary of Agriculture Henry A. Virts. "Large clusters of beetles gather on the outside of houses in October and early November. As the weather becomes colder, they enter cracks and gaps in the house to seek shelter. Some beetles will enter living areas, causing people to become concerned."

"The best thing one can do is collect the beetles, take them outside and release them in a pile of leaves," said Robert Rabaglia, forest entomologist with the Maryland Department of Agriculture. "These beetles are actually beneficial. Throughout the warm months, they eat aphids, insects that destroy a variety of garden and crop plants. A single immature lady bug can consume 300 aphids in a two-week period."

The multicolored Asian ladybird beetle (called Harmonia axyridis by scientists) was introduced by USDA agricultural research scientists in the late 1970's and early 1980's as a biological control agent in Louisiana and other southern states. It has since spread as far north as Quebec, Canada.

"The beetles do have one other unpleasant feature," said Rabaglia. "When stressed, they exude an orange liquid that is sticky and bad smelling. This is the beetle's defense against predators such as birds."

Rabaglia recommends that homeowners vacuum up beetles inside the house and take the bag outside. Release the beetles or store the bag in a cool place for later release. Using a broom is not recommended because it may result in orange spots on surfaces from the beetle's defensive liquid.

Posted: 11-9-2000