Left: Adult with full complement of spots. J.Ogrodnick
Center: Mature larva (fourth instar). M.H.Rhoades
Right: Typical adult H. axyridis color variation. R.Pienkowski

Harmonia axyridis
(Coleoptera: Coccinellidae)

Multicolored Asian Lady Beetle

The multicolored Asian lady beetle is an introduced biological control agent that is spreading rapidly throughout the United States. Despite the fact it is an effective biological control agent in agricultural and landscape environments, it has become a major nuisance to homeowners because of its habit of invading houses and buildings in large numbers while searching for protected sites to overwinter in the fall (mid-October to early November) and appearing again on warm, sunny days in February and March. In addition, beetles may get in picnic food and drinks, "swarm" like bees and land on people. For helpful insights in dealing with the Asian lady beetle if it becomes a nuisance, please see the information compiled from Ohio State University Despite these annoying traits, H. axyridis  preys upon many species of injurious soft-bodied insects such as aphids, scales, and psyllids and is thus considered beneficial to growers and agriculturalists.

The USDA made several releases throughout the eastern United States in an attempt to introduce this beetle into North America. It took a long time for releases made in Louisiana and Mississippi in 1979 and 1980 to become established and spread, but by 1994, H. axyridis  was found in Alabama, Georgia, South Carolina, and Florida. They are now widely disseminated in North America with frequent reports from the south, northeast, midwest, and as far as Oregon.

Although "multicolored Asian lady beetle" is the common name officially accepted by the Entomological Society of America, several other common names are also found in the literature: Halloween lady beetle (because of its pumpkin orange color and large populations often observed around Halloween), Japanese lady beetle (because Japan was the country of origin for specimens released in the southeastern United States), and Asian lady beetle.

Appearance

H. axyridis  occurs in many color forms. Adults are strongly oval and convex, about 6 mm long, and 5 mm wide. North American populations have a mix of individuals ranging in color from pale yellow-orange to bright red-orange, with or without black spots on the wing covers. The head, antennae, and mouthparts are generally straw-yellow but are sometimes tinged with black. The pronotum is similarly straw-yellow with up to 5 black spots or with lateral spots usually joined to form 2 curved lines, an M-shaped mark, or a solid trapezoid. The wing covers are generally yellow-orange in unspotted beetles. In fully spotted beetles, each wing cover has 10 black spots (see photograph).

Eggs are bright yellow, laid in clusters of about 20 on the undersides of leaves. Larvae are elongate, somewhat flattened, and adorned with strong tubercles and spines. The mature larva (or fourth instar) is strikingly colored: the overall color is mostly black to dark bluish-gray, with a prominent bright yellow-orange patch on the sides of abdominal segments 1 to 5.

Habitat (Crops)

A variety of nursery, ornamental, and field crops in North America, including cotoneaster, rose, Christmas trees, apple, pecan, alfalfa, wheat, cotton, tobacco, and small grains.

Pests Attacked

Many species of injurious soft-bodied insects such as aphids, scales, and psyllids, including pecan aphids, red pine scale, balsam twig aphids, and pine bark adelgid.

Life Cycle

It is believed that females overwinter in protected sites unmated, with the majority of the population mating later in the spring. Eggs generally hatch in 3 to 5 days. The larval stage lasts 12 to 14 days, and the pupal stage, which takes place on leaves, lasts 5 to 6 days. In cool spring weather, development from egg to adult can take 36 days or longer. After emergence, adults can live as long as 2 to 3 years under optimal conditions.

Relative Effectiveness

In Japan, Harmonia axyridis  is considered primarily an arboreal species and is common on various aphid-infested trees and bushes such as maple, walnut, willow, and rose; it is also an important predator of various destructive scales in Japan and mainland China. An adult is capable of consuming 90 to 270 aphids per day, and each larva can consume 600 to 1,200 aphids during its development. H. axyridis  is a promising biological control agent of several insect pests on a wide variety of ornamnental and agricultural crops. Its large, and even explosive, populations are probably caused by the massive abundance of prey (predominantly aphids and scales), apparent lack of competition from native lady beetles, and apparent lack of native natural enemies. Scientists predict that multicolored Asian lady beetle populations will become more balanced when its prey numbers decrease and Harmonia  itself falls prey to native natural enemies.

Pesticide Susceptibility

Pesticides should not be used for controlling populations of H. axyridis.  The best technique for managing lady beetles is first to prevent their entry into houses and other buildings by sealing cracks and openings around windows, doors, siding, and utility pipes with a quality silicone or silicone-latex caulk. Similarly, repair door and window screens or other openings to the outdoors using regular window screening (about 18 X 16 mesh size). If beetles still gain entry into living spaces, they should be removed using a broom and dustpan, or vacuum cleaner, and released outdoors. When using a broom and dustpan, gently collect the beetles to avoid alarming them. If alarmed, they may discharge a yellow fluid that can stain walls, paint, and fabrics, and that has an unpleasant odor. All lady beetles do this reflex bleeding when alarmed. The blood comes out of the leg joints.

Commercial Availability

Not available commercially at this time.

Taken from:

Knodel, Janet J., and Hoebeke, E. Richard (1996) IPM Fact Sheet 101.00, Cornell Cooperative Extension, Cornell University.

Other references:

Mahr, Susan (1996) Know Your Friends: Multicolored Asian Lady Beetle, Midwest Biological Control News,  Vol. II, No. 10.

McCandless, Linda (1996) Lady bug, lady bug, fly away from my home!, Cornell University Station News,  Geneva, New York, Vol. LXXVII, No. 42.

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