Species: Multicolored Asian lady beetle (Harmonia axyridis); Lady beetles (family Coccinellidae); Two-spotted lady beetle (Adalia bipunctata); Pink spotted lady beetle (Coleomegilla maculata)
Side by side
| Multicolored Asian lady beetle | Other lady beetles | |
|---|---|---|
| Plate behind the head | White with a black W, sometimes filled to a solid patch; Maryland reads the same mark as an M | Penn State treats the white pronotum with a black W as the character that separates this species from many other lady beetles |
| Adult size | 9/32 inch (7 mm) long, 7/32 inch (5.5 mm) wide | Penn State describes most native lady beetle species as smaller than this |
| Color range | Tan to orange to red, plus black forms; 0 to 18 spots | Varies by species. Penn State names the two-spotted and pink spotted lady beetles among the natives in decline |
| Autumn behavior | Flies to buildings September through November and overwinters inside walls and attics | Kentucky notes that lady beetles are normally considered beneficial because they live outdoors |
| Diet | Larvae and adults are predators of aphids and scale insects | The same. Maryland describes lady beetles in general as predators that prey on pests such as aphids |
What to look for
- Size. Penn State gives the multicolored Asian lady beetle 9/32 inch (7 mm) long and 7/32 inch (5.5 mm) wide, and calls it larger than most native lady beetle species. Kentucky and Maryland extension both round the adult to about 1/4 inch (6 mm).
- The pronotum, checked before anything else. Penn State describes a white pronotum bearing a black W that can fill in to a solid black patch in dark individuals. Maryland describes the same marking as a pair of white marks forming an M.
- Color and spots settle nothing on their own. Penn State records red wing covers with up to 18 black spots, forms reduced to four spots, forms with no spots at all, and black forms carrying two, four or twelve orange to red spots.
- Body shape. Penn State describes the adult as oval and convex, like other lady beetle species.
- Larvae. Penn State calls them alligator-like, dark grey with rows of orange markings and double-branched spines. Maryland describes black larvae with two lateral orange stripes, covered in small flexible spines.
- Where you found it. Kentucky notes that beetles indoors crawl on windows, walls and attics after flying to buildings in autumn, and that they are the same individuals that entered the previous fall.
Where and when
Kentucky extension reports swarms flying to buildings from September through November, with most Kentucky movement in October, on sunny days following cooler weather once temperatures return to at least the mid-60s. Beetles gather on the sunnier southwest walls. Penn State puts the start of overwintering around the beginning of October, and describes tens of thousands congregating in attics, ceilings and wall voids.
Does it matter?
Kentucky extension says these beetles do not reproduce indoors and do not attack wood, food or clothing. Both Kentucky and Penn State report that they occasionally bite or pinch, and that infestations have been linked to allergic reactions ranging from eye irritation to asthma. If you think you are reacting, ask a doctor. Disturbed beetles release a yellow fluid that stains. Kentucky's advice is sealing cracks before autumn.
Related guides
- Carpet beetle: Carpet beetles are small oval beetles, 1/16 to 1/8 inch long, that Kentucky extension describes as black or mottled with white, brown, yellow and orange.
- Boxelder bug: A boxelder bug is a black true bug with thin red lines, about half an inch long, that gathers in numbers on the sunny side of a wall in autumn.
- Stink bug: The brown marmorated stink bug is a shield-shaped brown bug about 17 mm, or two thirds of an inch, long and almost as wide as it is long.