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Be careful

Asian lady beetle

Harmonia axyridis
Also called multicolored Asian lady beetle, Asian ladybug, Halloween lady beetle, Japanese ladybug

It can give a small pinching bite and leaves a smelly yellow stain when disturbed, and swarms indoors can set off allergies in some people, but it carries no disease.

Asian lady beetle, photo 1
Photo: Sascha Nunheim, CC BY 4.0, via iNaturalist
Size6–7 mm (about 1/4 inch) long
Where in the houseWindows and walls, attic, living room, outside near the house
WhenOctober and November when they move in, and again on warm days from February to April when they try to get back outside.

Check these features

  1. Rounded, domed oval beetle shaped like a typical ladybug
  2. Color ranges from pale yellow-orange to deep red, with anywhere from zero to about 18 black spots; some are black with red spots
  3. White area just behind the head with a black mark shaped like an M or W (depending on which way you look)
  4. Gathers in groups on sunny walls and windows in fall

Bites and stings

It may give a small pinch that can sting a little and occasionally breaks the skin on tender areas. Wash the spot with soap and water. Some people get itchy skin from the yellow fluid, and people with allergies or asthma may notice symptoms when many beetles are indoors. Get medical care for wheezing, trouble breathing, or swelling of the face; call 911 if breathing is hard.

What to do

  1. Vacuum the beetles up instead of sweeping or crushing them, which makes them release a smelly yellow fluid that stains.
  2. Empty or seal the vacuum bag right away and take it outside so beetles do not crawl back out or start to smell.
  3. Look for where they are getting in, starting in the room with the most beetles: gaps around window frames, baseboards, light fixtures and ceiling fans.
  4. Plan to seal outside cracks before next fall; indoor sprays and foggers do not give lasting relief.

Look-alikes

Native lady beetlesNative ladybugs are usually a bit smaller and lack the clear black M or W mark on the white patch behind the head, and they rarely invade homes in large groups.
Boxelder bugBoxelder bugs are flat and long rather than round and domed, black with thin red lines instead of spots.

Why it came inside

In fall the adults look for a sheltered place to spend the winter and gather on sunny south- and west-facing walls, then slip through gaps into attics and wall spaces. Warmth from the house draws some of them into rooms, and they do not breed indoors.

Keep it out

  • Before late September, caulk cracks around windows, doors, siding, pipes and chimneys.
  • Repair torn window and door screens and add weatherstripping or door sweeps where light shows.
  • Cover attic, soffit and exhaust vents with fine screen mesh.
  • Do not spray inside wall voids; dead beetles left there can attract carpet beetles.

What helps

Links go to Amazon search results so you can compare current options. As an Amazon Associate I earn from qualifying purchases. Always follow the product label.

Vacuum with a hose

Lets you remove bugs, webs and egg sacs without touching them. Empty the bag or canister outside right away.

See options on Amazon
Caulk and sealant

Silicone or siliconized acrylic caulk closes cracks around windows, pipes and baseboards. Bigger gaps need foam backer rod or expanding foam first.

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Weatherstripping

Seals the gaps around doors and windows that let in drafts and bugs alike.

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Door sweep

Closes the gap under an exterior door. If you can see daylight under the door, bugs can get in.

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Screen repair kit

Patches or replaces torn window and door screens, one of the most common ways insects get in.

See options on Amazon

Sources

  1. Penn State Extension
  2. Clemson Cooperative Extension Home & Garden Information Center
  3. University of Minnesota Extension
  4. Washington State University Extension (PestSense)

Checked October 18, 2026. Rating backed by 4 sources. How we rate danger.