- Contact information
- DNR forest health staff
Multicolored Asian lady beetle
Know your friends
Multicolored Asian lady beetle, sometimes called the Halloween lady beetle, was brought from Japan to control aphids on trees. It does good work, though can be a nuisance to people when its populations are very high.
Where multicolored Asian lady beetle has been found
The multicolored Asian lady beetle is originally from Japan. The U.S. Department of Agriculture released this beetle several times in the eastern United States to control tree aphids. It took a long time for the releases made in Louisiana and Mississippi in 1979 and 1980 to settle in and spread but by 1994 the beetle was found in Alabama, Georgia, South Carolina and Florida. Now it is in many locations throughout the Midwest.
Multicolored Asian lady beetle - what to look for
Multicolored Asian lady beetle (Harmonia axyridis) is a yellow to orange colored lady beetle that is often seen in large congregations on buildings around the end of October, giving it one of its common names the Halloween lady beetle. The adult lady beetle can vary in appearance--from a pale yellow-orange to a deep orange-red--and have from none to more than 20 black spots. They are very prolific and may live up to three years.
Where they mature and live
The bright yellow eggs are laid in clusters of about 20 on the undersides of leaves. The eggs hatch in three to five days and the larvae feed up in the trees for 12 to 14 days. They then pupate on the leaves, transforming into adults in five to six days. The multicolored Asian lady beetle lives in various trees, including maple, walnut, willow and oak, and feeds on various aphids, certain scales and a few other insects.
How multicolored Asian lady beetles help us
The multicolored Asian lady beetle is an effective predator of aphids on pecans, pine trees, ornamental shrubs, roses and other plants. In many areas pecan growers no longer need to spray their trees for pecan aphid because this lady beetle has done such a good job of biological control. Beetle populations tend to explode when there is an abundance of aphids, often eliminating the local aphid population.
But they can be a nuisance
Even though this lady beetle is an important biological control agent, it can become a nuisance when large numbers gather on homes or other buildings. For several days during autumn they usually cluster on sunny, southwest sides of light-colored rock outcroppings or structures where nearby crevices serve as overwintering sites.
Homeowners complain when there are thousands of beetles covering their house. People may have to walk across piles of them on the deck, pick them out of picnic food and drinks, deal with them "swarming" like bees and landing on people. The beetles are especially unwanted when they get in the house by crawling through openings such as uncaulked window frames. Outdoor crowds of the beetle may leave on their own after a few days or weeks.
How to prevent Multicolored Asian lady beetles from getting into your house
The best way to prevent beetles from becoming uninvited houseguests is to seal cracks around windows, doors, siding, utility pipes or other openings with a quality caulk. Replace or repair damaged screens and install screens over roof vents. Indoor crowds of beetles can be removed with a vacuum cleaner with a crevice tool. They can also be swept up with a broom and dustpan and be put outside, away from the house.
Killing them with insecticides, squashing them or handling them may result in orange stains on walls and fabric. When stressed, the lady beetles secrete a harmless (but staining) orange substance. This liquid is actually blood that comes out of the joints of the legs. This is called reflex bleeding and all lady beetles do this when stressed.
-Susan Mahr, University of Wisconsin - Madison