This variably colored and spotted lady beetle is an effective, natural control for harmful plant pests such as aphids, scale and other soft-bodied arthropods. Still, its tendency to overwinter in homes and other buildings, sometimes in large numbers, may make them a nuisance to many persons.
If agitated or squashed, the beetles may exhibit a defensive reaction known as “reflex bleeding,” in which a yellow fluid with an unpleasant odor is released from leg joints. This reaction generally prevents predators, such a birds, from eating lady beetles. But in the home, the fluid may stain walls and fabrics.
Multicolored Asian lady beetles are beneficial insects. Their natural control of aphids in pecan orchards has decreased insecticide use against those pests. Additionally, they have controlled aphids on some ornamental plants. Still, these lady beetles are unwelcome guests for many homeowners.
Lady beetles have four distinct life stages: egg, larva, pupa and adult. The multicolored Asian lady beetle adults begin laying eggs on host plants in early spring. Eggs hatch in about three to five days, and larvae begin searching on plants for aphids and other soft-bodied arthropods on which to feed. Adults and larvae typically feed upon the same prey. Larvae molt four times, becoming larger after each molt, and enter an immobile pupal stage after the last molt.
After several days, the adult beetle emerges from the pupal case. Development time from egg to adult requires about 15-25 days depending on temperature and food availability. Later in the fall, near the time of killing frosts, the adult beetles seek shelter to spend the winter.