Guardian Pest Solutions

Multi-colored Asian Lady Beetle
Harmonia axyridis Pallas

Description

The Multicolored Asian Lady Beetle is native to Asia but occurs in many areas of the United States now. This beneficial insect was imported and released a few times in attempts to introduce as biological control agent against certain pests such as aphid, scale insects and many other insects in agricultural field, nursery and garden.

Adult beetles are approximately 0.2 to 0.3 inches long. They have a typical domed, round to oval ladybug shape. The name “multicolored” refers to the many different color forms of the adult beetles. The most common colors are red or orange with black spots, black with 2-4 red spots and yellow with faded black spots. Most of them have several spots on the pronotum that fuse into an irregularly-shaped “M”.

Importance

Multicolored Asian Lady Beetles prefer to live on trees in forested area; their population typically builds up during cool, wet summers that favor healthy plant foliage and large aphid infestations. Larvae of these beetles feed on aphids and soft-bodied insects during the summer and turn into adults in late summer. One larva can consume up to 1200 aphids in its life stage. Adult beetles can live up to 2-3 years.

The major concern that people have is the presence of these beetles is a nuisance. When temperature drops down, they start to seek places for overwintering. They are attracted to lighter colors on the structure for sunlight and warmth: whites, grays, yellows and can gather around the building in large numbers. Despite the annoyance, they are not structure-damaging pests; they do not chew or bore holes in walls or eat carpet or furniture. They do not lay their eggs in homes.  Once they enter the walls of a building through cracks and crevices, they may or may not proceed to the interior of the building. Most stay in the wall spaces till next spring.

During warm days of late winter and early spring, overwintering beetles in the wall void may become active. Higher temperatures or lighting in the living areas may attract these active beetles as they search for an exit.

Other problems associate with the lady beetles include stains and odor; when disturbed, their will exclude an orange- red color fluid as a defensive mechanism. This fluid has a foul odor and can permanently stain walls, carpeting and etc. Do not crush or sweep them when they are alive. Use vacuum to pick up live beetles that has gathered against wall or inside structure.

Control methods

The best management recommendation is to prevent multicolored Asian lady beetles from entering the structure. Preventive measures include sealing openings, caulking, screening and filling holes, joints with foam filler should be done before late autumn to exclude the beetles. Once inside, vacuuming is the best way to remove them.