Asian Lady Beetles (Harmonia axyridis (Pallas))
Asian Lady Beetles are also known as multicolored Asian, Halloween, or Japanese lady beetles. Though not native to the U.S., they are well established in many states, and large numbers of lady beetles (ladybugs) may be found around homes and other buildings during the fall. Reports of hundreds to thousands of these beetles, congregating on sunny outside walls, windows, doors, porches and decks, are not uncommon. They can be a serious nuisance when they get indoors. Blood stains and foul odors are among the most notable problems associated with these beetles.
General Biology
Multicolored Asian lady beetles are oval, about 1/4 inch long, 3/16 inch wide, range in color from yellow to orange to red, and may be spotted or have no black spots on their bodies. They do not carry human diseases, damage wood, clothing or food, but may cause inhalant allergies in some people. Inhalant allergies clear up once the lady beetles are removed. People may also be sensitive or allergic to the fluid (blood) that lady beetles secrete, which can cause contact dermatitis and a stinging sensation. More rarely, the beetles may bite, and can draw blood on tender skin. They do not reproduce indoors, but dozens can appear inside from overwintering populations.
During the fall, adult beetles may cluster together to overwinter in sheltered locations. After finding a suitable spot, they release a chemical known as a pheromone, which attracts more Asian lady beetles to the same location. Afterwards they all may begin to move to shelter. As spring approaches the beetles are often seen during, warm, sunny days when they leave a sheltered spot, such as a house, to return to their outdoor habitat.
Despite the sometimes annoying populations, these insects are considered very beneficial to agriculture. They feed on harmful aphids and some scale insects associated with desired crops, trees, bushes, and ornamentals, like roses. They were actually released as an insect predator by the United States Department of Agriculture between 1977 and 1981. Those seen now are thought more likely associated with accidental introduction.
CONTROL OPTIONS
· Chemical insecticide application is not a primary recommendation, though some temporary relief may be gained. Vacuuming is generally the best method to use in and around homes. Known as reflex bleeders, they ooze reddish blood from the joints of their leg when handled or disturbed. Sweeping them up will cause them to bleed. The blood has a bad odor and can also stain anything it contacts. If chemical application is chosen, it should be done prior to the establishment of the beetles in the structure, using rapid action pesticides.
· Vacuum as soon as possible, to reduce the attraction of others. Remove the bag from the vacuum immediately to prevent crawling back out or the foul odor produced by their death after a few days. They can be released away from your home, in natural areas to benefit growers the following spring.
· Prevent entry by using caulk or weather strip to seal exterior cracks and openings the beetles may use to enter your building. Check for openings in soffits and siding, and repair screens on windows, doors and attic vents. This can be difficult, and perhaps impractical, since the beetles can enter relatively small openings, and sealing some construction types is beyond the skills of the average homeowner.
· Always read the label and follow directions and safety precautions before using any pesticide.