Published: October 28, 2009 06:24 pm         

Large numbers of beetles swarming this fall

TERRE HAUTE — 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 beetle population parallels the growth of the aphid population because that’s one of its favorite foods.

Unlike regular ladybugs, the multicolored Asian lady beetle is 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 southeastern United States, they have greatly expanded their habitat. They provide natural biological control of scale and aphids. This provides both economic and environmental benefit to 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 orangeish 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. In their native Japan, the beetle overwinters as an adult in cracks and crevices of cliffs and rocks. As far as the beetle is concerned, your home looks like a big cliff and a great place to overwinter. The beetles also bite and emit a strong, disagreeable odor if disturbed.

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.

For more information, contact Suzanne Bissonnette at sbissonn@illinois.edu or at (217) 333-4901.