The Common Confusion: Do Ladybugs Bite People?
The classic ladybug, belonging to the Coccinellidae family, is primarily known for consuming destructive pests like aphids and scale insects. Given their reputation as harmless garden protectors, the public’s confusion about whether they bite is understandable.
The direct answer to whether a ladybug can bite is technically yes, as they possess small chewing mouthparts called mandibles, but native species rarely, if ever, use them on humans. The insect responsible for nearly all reports of a “ladybug bite” in North America and Europe is the Multicolored Asian Lady Beetle (Harmonia axyridis), an invasive species introduced to control agricultural pests. While native ladybugs are typically gentle and prefer to avoid contact, the Asian Lady Beetle exhibits a tendency toward seeking moisture or salt, which leads it to make contact with human skin. This distinction is the source of the common confusion, as many people mistake the invasive species for their native counterparts.
How to Identify the Asian Lady Beetle
Distinguishing the Asian Lady Beetle (ALB) from native ladybugs relies on physical and behavioral characteristics. The most reliable visual marker is the presence of a dark, M-shaped or W-shaped marking located on the whitish area immediately behind the head, known as the pronotum. This marking can appear thick, thin, or even broken, but it is a consistent feature on the ALB that is absent on most native species.
The coloration and spot count of the Asian Lady Beetle are highly variable, making those features less reliable for identification. They can range in color from pale yellow or orange to deep red, and may have anywhere from zero to 19 black spots on their wing covers, or elytra. Native species often have a more consistent, true red color. The ALB tends to have a slightly more oval, elongated body shape, while native ladybugs are generally more rounded. The most noticeable behavioral difference occurs in the autumn when the ALB seeks out overwintering sites, often aggregating in large numbers on the sunny, warm sides of buildings before finding their way indoors.
Why They Bite and What to Expect
The motivation for the Asian Lady Beetle to bite a person is not predatory, but a search for resources. The insect may use its mandibles to scrape the skin in an attempt to acquire salt or moisture, especially during dry periods or heat waves when water is scarce. This exploratory action is not intended to be harmful, but it is what is commonly perceived as a bite.
The sensation of a bite from an ALB is a mild, momentary pinch or a pinprick, which rarely breaks the skin. Because the beetle is not venomous, the bite itself is not medically significant and usually results in a temporary, small, red bump or minor irritation. The beetle’s defensive mechanism, known as “reflex bleeding,” is a concern. When disturbed or crushed, the beetle exudes a foul-smelling, yellow-orange fluid (hemolymph) from its leg joints. This hemolymph contains defensive alkaloids and can leave a difficult-to-remove stain on walls, furniture, or fabrics indoors, which is why vacuuming them up and disposing of the bag is the recommended method of removal.