Key points
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In general, lady beetles (ladybugs) are considered beneficial insects (predators) because they prey on insect pests such as aphids.
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The multicolored Asian lady beetle, a native of Asia, was initially released in California in the early 1900s. It was subsequently released a number of times from 1978 to 1985. From these later releases, it became permanently established in the United States. It is now a common visitor in and around homes and gardens in Maryland.
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The multicolored Asian lady beetle can be distinguished from other species of lady beetles by a pair of white markings behind the head (on the pronotum) that forms the shape of an “M”.
General information
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This lady beetle resembles native lady beetles in appearance. The adults are approximately ¼ inch long. They vary in color from pale yellowish brown to bright orange-red. The pattern of spots is variable with most adults having 19 on the elytra. Some beetles may have faint spots or none at all.
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The larvae are “alligator-shaped” like most lady beetle larvae. They are black with 2 lateral orange stripes and covered with small flexible spines. Both larvae and adults feed on aphids and scale insects.
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This beetle is primarily a tree inhabitant but is also found in orchards, field crops, and gardens.
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The life cycle from egg to adult takes about a month in warm weather. Eggs hatch in 3-5 days and larvae feed for 12-14 days. Larvae then pupate, which takes another 5-6 days. Adults can live 2-3 years.
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Adults overwinter in sheltered sites and mate in the spring.
Problem
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Its habit of seeking indoor sheltered overwintering sites in the fall has made it a nuisance in and around homes and buildings.
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Adults apparently secrete an aggregation pheromone, which results in large numbers of beetles gathering at favorable sites. Favorable sites include attics, basements, and living areas of homes.
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On warm sunny days during the winter adults may fly towards windows and be seen walking on walls and ceilings.
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Do not swat or crush the lady beetles because they release a yellow-orange liquid that can stain fabrics and walls.
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Adult beetles can also be a minor pest on ripening fruit such as apples, peaches, grapes (especially wine grapes), etc. But control is not needed or recommended.
Management
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Prevention is the best way to manage the problem of beetles entering the home.
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In late summer and early fall, caulk cracks and seal any entry points around windows and install screening over vents.
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If the beetles do enter the home, simply vacuum them up and release them outdoors.
Based on publication HG 49 The Multicolored Asian Lady Beetle, author Author, Mary Kay Malinoski, Extension Specialist, Entomology (retired), HGIC 2020.