Facts, Identification & Control
Harmonia axyridis (Pallas)
Multicolored Asian lady beetles are common throughout most of the United States and parts of Canada. The scientific name is Harmonia axyridis (Pallas). This is one of a very large family of beetles known as Coccinellidae. Many people call these beetles “ladybugs.”
Multicolored Asian lady beetles are about 7 mm long. As the name indicates, they occur in a wide spectrum of colors ranging from yellow to orange to red and have a varying number of spots. The variability of appearance in the adults can mislead people to think they are different species. A characteristic that assists in their identification is an “M” shaped marked located behind the head.
Behavior, Diet & Habits
There are many species of Coccinellidae in the U.S. and Canada. Most are beneficial insects. Plant specialists imported several species of lady beetles into the United States to control crop pests. The adults and larvae of most lady beetles are predators of aphids, mealybugs and scale insects.
In the fall, multicolored Asian lady beetles gather in large numbers on the outside of light-colored houses. As they gather on the house, some find cracks or holes. They use these holes to get inside. Some lady beetles enter quiet places like the attic. They hibernate through the winter and become active again in spring.
Eggs are deposited by females on the underside of plant leaves. The larvae emerge and will search for insects on the plant to prey upon. They eventually will pupate into adults. The time from egg to adult varies with environment and resource availability but typically is 15 to 25 days.
Signs of an Asian Lady Beetle Infestation
The most troubling sign of the multicolored Asian lady beetles is the mass appearance of large numbers of adults on and around buildings. This occurs during the fall with renewed activity on warm winter days and again in the spring. The larvae may be seen on plants or outdoor surfaces but, due to their radically different appearance from the adults, may not be recognized.
The vacuum cleaner is the simplest way to remove the lady beetles that get into the home. They can bite, but it usually is more startling than harmful. They do not reproduce or feed during their overwintering inside the home.
During the summer, homeowners can prevent many lady beetle problems. Inspect the outside of the house carefully. Caulk cracks around windows and doors. Check the attic, roof and overhang vents. Repair any damaged screens. Check the weather stripping on all exterior doors. Repair any damaged window screens. Inside the home, patch any holes that lead into the attic.
Insecticide application on the outside of the home will act as a barrier. It will repel many of the pests that gather on the home and keep them from entering. The application should begin in the late summer. Because of temperature and other factors, the barrier will need to be re-applied periodically. The pest control professional has the equipment to make this treatment.