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near Cofrin Arboretum, Brown County, WI
15 October 2000
Amy Wolf / Bob Howe / Gary Fewless
Olympus CL 2500L digital camera

Multicolored Asian lady beetle

Multicolored Asian Lady Beetle

This October Wisconsin has been invaded by swarms of "ladybugs" like the ones shown in this photograph. Lady beetles are predatory beetles that feed on aphids and other soft-bodied plant eating insects. Although we have several species of ladybugs in Wisconsin, the species most abundant now is the Multicolored Asian Lady Beetle, a native of China, Japan, and other parts of Asia. As the inset in the enlarged photo shows, individuals vary considerably in color from yellow orange to dark red, and can have 0 to 10 dark colored spots on each of the 2 wing covers. It is sometimes called the "Halloween" lady beetle because individuals are often pumpkin colored and are most commonly encountered during October.

The species was introduced into California in 1916 and reintroduced in the eastern US and Canada several times between 1977 and 1980 to control aphids. The first reports from Wisconsin were in 1992. Asian Multicolored Lady Beetles are particularly abundant here this year because of an outbreak of another Asian native, a soybean aphid. In their native habitat the beetles often gather together in the fall and hibernate in cracks on sunny cliffs, which may be why they are attracted to light colored walls and siding. Although they release an orange smelly defense chemical and might give a pinch-like bite if trapped, they are not poisonous and do not transmit diseases.

Most entomologists agree that pesticides are NOT very effective in controlling aggregating ladybugs. The best advice for coping with swarms of these insects is to be patient, they will be gone in a couple of weeks. Commercially bought or home made light traps and vacuuming are the recommended methods for removing ladybugs that get inside the house. Ladybugs that get into your house will eventually die because the humidity is too low. Applying pesticides now will only be expensive for you and add poisons to your yard and house. Indoor pesticides are ineffective because the beetles are hiding in inaccessible areas in the walls,. Outdoor preventative chemicals only work if applied before the beetles begin to congregate so application now is also ineffective. Stop up cracks in screens and vacuum or sweep the ladybugs under bushes or against walls, especially near gardens, where they can overwinter and help control insect pests in the spring. Because they eat the same food as other lady beetles, the most serious concern about the Asian Multicolored Lady Beetles is that they may outcompete and cause a decrease in the biodiversity of our 350+ native species.

 

Updated 20 October 2003

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Last updated on June 3, 2014