Common Insects and Mites: Asian lady beetle

Biology

Common in Japan, Korea, and other parts of Asia, the Asian lady beetle was introduced by USDA Agricultural Research scientists in the late 1970’s and early 1980’s as a biological control agent for pear psylla and other soft bodied insects. By the mid-1990’s, it had become established throughout western Washington. Being a recent introduction to the U.S., few natural enemies are available to limit its population. The species exhibits tremendous color variation, ranging from black with two red spots, to red with 19 black spots, and about every combination in between. With this tremendous variation, identifying and distinguishing them from many of our native lady beetles becomes rather difficult. Adults spend the winter months in clusters, protected from the weather, on walls with a south-southwest exposure. At 1/4″ long, they can enter wall voids through cracks and settle in for winter. Warm interiors draw them further inside, and they become a nuisance to homeowners. Some cases have reported lady beetles in food and waking up quietly sleeping people after crawling on them. Although these lady beetles are a particular nuisance during spring, they eventually move out to locate their natural prey–aphids, mites, and scales. By helping to control these common garden pests, they reduce our reliance on insecticides and therefore enhance environmental quality.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Use a USDA lady beetle trap. Beetles are attracted to a black light and captured in an attached bag. Insects are then collected alive for later release or disposal. Detailed technical instructions and diagrams for constructing the trap are available on an ARS web site in PDF (portable document format) at: http://www.ars.usda.gov/is/br/lbeetle/001030.trap.pdf
• Ensure tight-fitting screens, windows, and doors. Locate entry points and seal up cracks and crevices via caulking. Concentrate efforts on south and west faces of infested structures.
• Vacuum complete clusters from walls during autumn. Dispose of vacuumed beetles far away from the building; otherwise they will return.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

None recommended. Lady beetle carcasses will remain in wall voids where other insects, such as carpet beetles, can use them for food. Upon depletion of this food source, they can readily move into homes and feed on valuable interior items. Once established, carpet beetles can be difficult to exterminate. Lady beetles are beneficial insects and should be preserved, if possible.

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