Field plate · Harmonia axyridis
Multicolored Asian lady beetle
Orange-to-red dome beetles with highly variable spots — and a black M-shaped mark behind the head. They bite gently and stain.
Plate 8 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
Dome-shaped, 6–9 mm, colour ranging from pale orange to deep red, with anywhere from no spots to nineteen. The reliable mark is the black, M-shaped pattern on the white pronotum just behind the head.
Look-alikes it is confused with
Native lady beetles, which are generally redder, lack the M mark, and rarely invade houses in numbers. Also confused with boxelder bugs in the same autumn wall gatherings, though the shape is entirely different.
Where it hides in a house
South and west walls in October, then window frames, attics, and wall voids. They emerge indoors through winter and spring, drawn to light rooms and pale paint.
Health & property risk, stated plainly
They can give a small pinch bite, and when disturbed they bleed a yellow, staining, musky fluid from the leg joints that marks paint, fabric, and upholstery. In the vineyard and orchard country around Lake Erie they are also a harvest contaminant.
What actually works
The same autumn exclusion as for stink bugs: seal before the flights, vacuum — do not swat — indoor beetles, and fit screens. Vacuum bags should leave the house the same day.
What doesn't
Crushing them (that is what releases the stain and odour) and spraying inside a void where the dead will attract scavenger pests for seasons.
When to call a licensed pro
Call a pro when the house takes thousands each autumn and the entry points are high or hidden, or when beetles contaminate a food or rental space.