Large Numbers of Multicolored Asian Lady Beetles Bugging Everyone

FOR IMMEDIATE RELEASE
October 29, 2009

Large numbers of Multicolored Asian lady beetles are making their presence known. This growing season the weather was ideal for large numbers of soybean aphids to develop and multiply and the Multicolored Asian lady beetle population parallels the growth of the soybean aphid population because that's one of its favorite foods! Lots of aphids equal lots of lady beetles.

Unlike our regular lady bugs the Multicolored Asian lady beetle is a fairly large. Adults are roundish, one-quarter inch long, yellowish to orange to red beetles with zero to 19 black spots on the back. Originally introduced to control scale insects and aphids on ornamental plants in the south eastern United States they have greatly expanded their habitat. They provide excellent natural biological control of scale and aphids. It is hard to believe that there is a benefit to these bugs when they are crawling all over your house, your car, yourself, or your yard in the fall, but they provide tremendous service in managing a very serious pest on soybean here in Illinois called soybean aphid. This provides both economic and environmental benefit to our food production by reducing insecticide applications.

University of Illinois Extension Entomologist Phil Nixon notes that "Multicolored Asian lady beetle larvae feed on soft-bodied insects such as aphids and scale on trees, shrubs, and low-lying plants. When soybean aphids are numerous, very large numbers of these lady beetles are produced. Fully-grown larvae are about one-quarter inch long and look like tiny, black alligators with a yellow to orangish band across the middle of the body. They pupate on plants and later emerge as adults."

Fall is when the problems for the general populace begin. These beetles are quite lovely, but not very clever. In their native Japan, the beetle overwinters as an adult in cracks and crevices of cliffs and rocks and other similar cover. Well, we are not exactly covered with cliffs, or rocks or even much topography here in central Illinois. So, as far as the beetle is concerned your home looks like a big cliff and a great place to overwinter. They cross the line from beneficial insect to pesky nuisance when they try to move in with you. They are attracted to buildings where they enter cracks and crevices to overwinter, commonly entering the living space from the wall void or around windows. The beetle is not known to be specifically attracted to any particular type of house or siding, it just wants in a structure to overwinter. The beetles also bite and emit a strong, disagreeable odor if disturbed. The beetle is not attempting to eat you, again, it is not very clever and as far as it is concerned you could be an enormous aphid, so it takes a bite to find out. The bite pinches.

Adult lady beetles are primarily managed by caulking exterior cracks and crevices, particularly around windows and corners of the building, both corners that jut out and those that are recessed. Beetles indoors can be vacuumed and disposed of outdoors. Using a shop vacuum is easier for this purpose because it cleans out easily, and they can be smelly. Light traps for use indoors are available on the internet and in some stores, but are rarely effective unless they are the only light source at night. Find out how to build one on this USDA website http://www.ars.usda.gov/is/br/lbeetle/ .

In counties where soybean aphids were a fairly new pest the number of Multicolored Asian lady beetles is fairly alarming to many people. Typically, insecticide applications are not recommended however, with very large infestations Pyrethroid insecticide applications applied by professional pest control operators (exterminators) on the outside of the building along edges and around windows are effective. One spray usually provides season-long control.

Let's hope for a much lower soybean aphid population next season. In the meanwhile for low to moderate infestations' a caulk gun and a vacuum will be your best bet.

For more information contact Suzanne Bissonnette sbissonn@illinois.edu 217-333-4901 Champaign Extension Center.

Source: Suzanne Bissonnette, Extension Educator, Integrated Pest Management, sbissonn@illinois.edu