The multicolored Asian lady beetle is 1/3 inch in length; dome-shaped; yellowish-orange to red with variable black spots on the back. Deep orange is the most common color. This bugs typically has 19 black spots on its wing covers but these may be faint or missing.
Some multicolored Asian lady beetles have no spots at all. There may be fewer spots present when they are faint. There is a prominent black ‘M’ shape behind the head in most specimens. This ‘M’ can look thick, thin or even broken in appearance. Also look for the big false “eyes”—two white football-shaped spots behind the head. Also look for their mustard yellow or red coloration.
The Asian Lady Bug Beetles, “Harmonia axyridis” or more commonly called “ladybugs” are also known as Halloween Beetles, Asian Ladybird Beetles, Japanese Lady Beetles, Korean Lady Beetles, and Multicolored Asian Lady Beetles.
As soon as the weather warms in the spring, the multi-colored Asian lady beetles begin emerging from their winter quarters. They will continue to do this until they have all departed for the season. After they leave, they will look for food, mate and the females will begin laying eggs on foliage. A short time later both males and females will die.
Lady beetles go through four stages of life over an average of 20 days. They start as eggs, change to a larva, pupa and an adult with wings. Eggs are laid on host plants where the larvae can feed on aphids and other arthropods.
Beetles are known to eat about 300 aphids before they are adults! Multicolored Asian lady beetles like many plants such as: evergreens, apple and maple trees, alfalfa, wheat, cotton, tobacco, and small grains.
Larvae molt four times before becoming a pupa. These beetles can produce up to five generations in areas with extended periods of warm weather. Adult beetles can live as long as 2 to 3 years. Asian lady beetles follow their instinctive behavior and fly to sunny, exposed surfaces when preparing to hibernate through the winter. The time of beetle flight varies but is usually from mid-September through October (depending on weather). Light colored buildings and walls in full sun appear to attract the most beetles.
Asian lady beetles, like other accidental invaders, are “outdoor” insects that can be a severe household nuisance during late fall and winter. Wooded residential and industrial areas are especially prone to problems. They do not feed or reproduce indoors; they cannot attack the house structure, furniture, or fabrics. They cannot sting or carry diseases.
Lady beetles do not feed on people though they infrequently pinch exposed skin. Lady beetles may leave a slimy smear and they have a distinct odor when squashed. From the exteriors of buildings they crawl under siding and roofing and into cracks and gaps in foundations and around windows, doors and other openings. They may continue to move into the living areas of homes or they may spend the winter inside the attic or wall voids. Mild, sunny winter days can wake these dormant insects.
They become active and move into the home’s living quarters. Once spring arrives, the remaining lady beetles wake up and attempt to move outdoors. Not all succeed and many are trapped indoors. Multicolored Asian lady beetles do not reproduce indoors.
Ladybugs, in general, actively prey on aphids and other soft-bodied insect plant pests. Both adults and immature multi-colored Asian lady beetles kill significant numbers on these plant pests, especially aphids.
Additionally, the multi-colored Asian lady beetle aggressively pursues these plant pests that attack trees; more so than our native ladybugs. In 2000, the soybean aphid, an exotic aphid from China, was discovered feeding on soybean plants. In 2001, the multi-colored Asian lady beetle fed heavily on the soybean aphids and likely saved Michigan soybean farmers millions of dollars in harvest revenues and insecticides that didn’t have to be used to control losses to this aphid species.
Multi-colored Asian lady beetles are harmless. They cause no harm to a building or its contents, including people and pets. However, when they show up inside the house by the dozens or hundreds, they usually wear out their welcome. Some bite, most do not. Sometimes the Asian lady beetles bite skin, but often this stinging sensation is actually caused by small spurs on the beetle’s legs pricking skin as they move and evaluate whether or not the skin is a food source. The beetle does not carry disease nor does it have any toxin associated with its mouthparts. In most cases, the pain is short lived. If the bite concerns you, apply antiseptic to the site.
When multi-colored Asian lady beetles are agitated they give off a yellowish fluid that has a faint, foul odor. This is a defensive reaction to ward off predators. It is called “reflex bleeding.” The liquid is exuded from its legs and it can stain. It is possible to have an allergic reaction to the multi-colored Asian lady beetle. Prolonged exposure to infestations has been reported to cause allergic reactions in some humans (Yarbrough et al 1999, mangnan et al. 2002), and repeated exposure to dead lady beetles can cause an allergic reaction in some individuals. Patients have described itchy nose and eyes, sneezing, upper respiratory symptoms, and severe, persistent asthma.
Asian Beetle Control
Even though there are measures that can be taken to eliminate the beetles as they appear in the house, the long-term solution to eliminating your beetle “problem” in the house is prevention.
Outdoors preventative tactics
Beginning in the early fall, monitor the sunlit side of your buildings for swarming beetles. These are areas where they will collect prior to moving into hibernation sites. You can apply an insecticide registered for outdoor use. If it is practical, caulk obvious cracks and spaces where the beetles can gain access, check attic vent screens and repair if necessary, caulk wherever a pipe, conduit, telephone or cable TV wire goes through the siding, and ensure that the weather seal on basement windows is tight.
Indoors preventative tactics
Making the effort to eliminate points of entry from the outside into hibernating areas is helpful. The real key to prevention is to also conduct the same inspection on the inside walls and make repairs, where necessary. After all, you probably wouldn’t care how many multi-colored Asian lady beetles were hibernating under your siding, in your walls voids and attic if none of them entered your living space. Pay close attention and caulk all those places where pipes, conduits and wires come through the walls. Use a vacuum to eliminate the existing beetles.
Sealing exterior gaps and cracks around windows, doors, eaves, roofs, siding and other points of access before the beetles appear can prevent unwanted entry. Experience suggests, however, that comprehensive pest proofing is time-consuming, often impractical and usually not 100% effective. For large infestations with intolerable numbers of beetles, spraying pyrethroid insecticides such as permethrin or esfenvalerate to the outside of buildings when the beetles appear may help prevent pest entry. Homeowner insecticides other than pyrethroids usually do not provide satisfactory prevention. For insecticides to be effective, they must be applied before insects begin to enter buildings, which is early- to mid-October for multicolored Asian beetles. Common examples of insecticides available to the public include those containing cyfluthrin, cypermethrin, deltamethrin, or permethrin. Be sure the product you intend to use is labeled for use on the exterior of buildings. Apply the insecticide according to label directions to siding, foundation, windowsills, and door thresholds, paying particular attention to the south and west sides where the insects are most common.
Residual Insecticides, Aerosols, Dusts. Spray with the residual insecticides around eaves, attic vents, windows, doors, under-fascia lips, soffits, siding(including under lips) and any other possible points of entry, concentrating on the south and the southwest sides . Spray with fan pattern from a garden pump sprayer the southern and western walls is helpful when lady bug populations are high. Remember that heavy duty infestations require heavy duty treatments.
Dust can be used to treat wall voids if there is no insulation to impede the spreading of the dust. It can also be placed around switch plate covers and electrical outlets as well as plumbing openings. The dust and aerosols should be applied to indoor cracks, crevices, wall voids, hiding places and entry points.