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How to identify it
- Oval and convex, about 1/4 inch long, larger than most native lady beetles; color ranges from tan to orange to red, with anywhere from no spots to many. Penn State gives 9/32 inch (7 mm) long by 7/32 inch wide and Clemson about 1/4 by 3/16 inch. Penn State says most have red wing covers with up to 18 black spots, while some forms are black with two, four or twelve orange to red spots.[1][2][4]
- Most have a dark M- or W-shaped mark on the whitish area behind the head. Penn State and Colorado State describe that area as white; in dark beetles the mark may be filled in to a black patch.[1][2][5]
- Larvae are shaped like tiny alligators. Kentucky describes them as often orange and black, Penn State as dark gray with rows of orange markings and double-branched spines, and Colorado State notes their prominent fleshy spines. Pupae are orange with black spots and may cling to walls.[1][2][5]
- Eggs are yellow and oval to oblong, laid in clusters on the undersides of leaves.[1][2]
Look-alikes
Where it lives
Native to Asia and established in North America since 1988; now across much of the U.S. and Canada. Homes near woods or fields are especially prone to fall swarms.[1][2]
Biology and life cycle
Swarms fly to buildings from September through November on sunny days after cool spells, gathering on sunny southwest walls and contrasting light-dark trim. Penn State says gathering starts around the beginning of October on a sunny, warm afternoon after a cold night, and Clemson says adults cluster in October and November and release a pheromone that draws others to the same spot.[1][2][4]
They overwinter in wall voids, attics and around windows, and wander indoors on warm days in late winter and spring; they don't reproduce indoors. Penn State says tens of thousands can gather in attics, ceilings and wall voids, and Clemson says they show up again in February and March on bright, warm days as they try to get back outside.[1][2][4]
Larvae and adults eat hundreds of aphids a day; individuals can live up to three years. Penn State says adults typically live 30 to 90 days. Development from egg to adult takes about one month (Kentucky) or three to six weeks (Penn State), with four to six generations a year in Penn State's account.[1][2]
Sources tell the introduction story differently. All agree the first established U.S. population was found in Louisiana in 1988, and each says it may have arrived by accident on a ship rather than from the release programs. Kentucky dates USDA release attempts to the 1960s through 1990s and Clemson to 1977 through 1981, while Penn State says releases began in California in 1916 and became more frequent in the 1970s and 1980s, but none appear to have established.[1][4][2]
Penn State says it is displacing native lady beetles, including the two-spotted and pink spotted lady beetles, probably by competing with them for the same prey.[2]
Damage and signs
- Disturbed beetles release an acrid odor and a yellowish fluid that stains surfaces; they don't damage wood, food or clothing. Clemson says they don't feed on wood, clothing or food and don't carry human diseases. Penn State notes that pets that eat the beetles may get chemical burns inside the mouth.[1][4][2]
- Beetles crushed with grapes at harvest cause "lady beetle taint" that can make juice or wine unmarketable. They also feed on fruit such as apples, peaches, pears and raspberries, but Penn State says they mostly go after fruit already damaged by something else.[2][1]
Health risk
Allergy studies have tied the beetles to reactions in some people. In a survey of residents of infested homes in Kentucky, 50% reported ladybug allergy and 19% reported symptoms on direct contact, while a later review cites a prevalence of 10% in one area where the beetle is common. Researchers found IgE antibody to two Asian lady beetle proteins in patients living in infested houses, and the review lists rhinoconjunctivitis, asthma, urticaria (hives) and angioedema (swelling), with allergy peaks during the fall swarms and smaller spring dispersals. The beetles also occasionally bite or pinch; Kentucky says it feels like a pinprick.[6][7][8][1]
Control
Keep them out
Seal cracks around windows, doors, soffits, fascia and utility lines in late spring or summer, screen attic vents and install tight door sweeps; gaps of 1/8 inch let beetles in. Penn State also says to cover attic, fireplace chimney and exhaust vents with number 20 or finer screen mesh, and Clemson adds checking lap siding for large cracks.[1][2][4]
Traps and physical control
Vacuum beetles indoors rather than sweeping, which causes staining; a handkerchief between the hose and bag lets you release them outside. With a bagless vacuum, Penn State suggests a nylon stocking held in the hose with a rubber band. Remove bags right away so the beetles don't crawl back out (Clemson), or freeze or discard them (Penn State). Penn State notes that people allergic to the beetles may not be able to vacuum them, because the vacuum exhaust spreads their odor.[1][2][4]
Light traps can catch beetles in dark spaces such as attics but catch few in living areas, and Kentucky says lady beetle "houses" won't keep them out of your home.[1]
Pesticides
Indoor sprays and foggers are not recommended; they're ineffective and may stain. A professional exterior treatment around entry points in fall can reduce entry where sealing is impractical. Penn State and Kentucky time exterior treatments for late September to early October, before the beetles move in; in late winter they are already inside, so barrier sprays don't help. Penn State warns that killing beetles inside wall voids can leave food for carpet beetles.[1][2]
Common questions
- Are Asian lady beetles breeding in my house?
- No. The beetles you see in spring are the same ones that came in the previous fall. Clemson also says they do not reproduce indoors.[1][4]
- Do Asian lady beetles bite?
- Sometimes. Kentucky says they occasionally bite or pinch when they land on skin and that it feels like a pinprick, and Clemson says they can draw blood on tender skin. Penn State says it is unknown why they bite people.[1][4][2]
- Can Asian lady beetles cause allergies?
- Yes, in some people. Studies from infested areas found IgE antibody to lady beetle proteins and reported eye and nose symptoms, asthma, hives and facial swelling. A review says avoiding exposure is the main treatment.[7][8]
- Should I buy lady beetles to release in my garden?
- Usually not. Penn State says these beetles are almost always already around, and released adults tend to fly off in search of food when aphid numbers are low.[2]
Sources
- University of Kentucky Entomology, “ENTFACT-416: Asian Lady Beetle Infestation of Structures.” entomology.mgcafe.uky.edu/ef416 (accessed 2026-11-11)
- Penn State Extension, “Multicolored Asian Lady Beetle.” extension.psu.edu/multicolored-asian-lady-beetle (accessed 2026-11-11)
- iNaturalist, “Harmonia axyridis taxon page (order and family).” www.inaturalist.org/taxa/48484 (accessed 2026-11-11)
- Clemson Cooperative Extension Home and Garden Information Center, “Multicolored Asian Lady Beetle (HGIC 2437).” hgic.clemson.edu/factsheet/multicolored-asian-lady-beetles/ (accessed 2026-11-11)
- Colorado State University Extension, “Lady Beetles.” extension.colostate.edu/resource/lady-beetles/ (accessed 2026-11-11)
- Annals of Allergy, Asthma & Immunology, via PubMed, “Sharma et al. (2006), Ladybug hypersensitivity among residents of homes infested with ladybugs in Kentucky, Ann Allergy Asthma Immunol 97(4):528-531.” pubmed.ncbi.nlm.nih.gov/17069109/ (accessed 2026-11-11)
- Journal of Allergy and Clinical Immunology, via PubMed, “Nakazawa et al. (2007), Asian ladybugs (Harmonia axyridis): a new seasonal indoor allergen, J Allergy Clin Immunol 119(2):421-427.” pubmed.ncbi.nlm.nih.gov/17291858/ (accessed 2026-11-11)
- Allergy and Asthma Proceedings, via PubMed, “Goetz (2008), Harmonia axyridis ladybug invasion and allergy, Allergy Asthma Proc 29(2):123-129.” pubmed.ncbi.nlm.nih.gov/18430308/ (accessed 2026-11-11)