Ladybugs are often seen as beneficial insects in gardens, helping to control pests like aphids. A common question is whether ladybugs bite. While native ladybugs rarely bite humans, the Asian lady beetle, a species often confused with native ladybugs, is known to bite. These beetles were introduced to control agricultural pests and exhibit behaviors that can lead to human interaction.
The Biting Truth
While native ladybugs are not inclined to bite, Asian lady beetles (Harmonia axyridis) do. These insects may bite if they mistake human skin for a food source, seek moisture or salt, or are disturbed. An Asian lady beetle bite feels like a mild pinch or pinprick. It typically causes a small, raised red bump that is usually harmless and resolves quickly.
The bite is rarely painful enough to break the skin or cause serious injury. Unlike mosquitoes or other blood-feeding insects, Asian lady beetles do not transmit diseases. While their chewing mouthparts can nip, the experience is more of an irritation than a deep wound. Any minor swelling or irritation is usually temporary.
Identifying Common Biters
Distinguishing between native ladybugs and Asian lady beetles is important, as the latter is the primary biting species. Asian lady beetles often range in color from orange to yellow, though they can also be red, unlike the true red of many native ladybugs. They are also slightly larger and more oval-shaped compared to the rounder native species.
A distinct feature of the Asian lady beetle is the black “M” or “W” shaped marking on the white area behind its head, known as the pronotum. This marking can vary in prominence but is a reliable identifier. Asian lady beetles also tend to congregate indoors in large numbers, especially during autumn, seeking winter shelter. Native ladybugs typically overwinter outdoors and are more solitary.
When disturbed or crushed, Asian lady beetles emit a foul-smelling, yellowish fluid from their leg joints, a defensive mechanism called “reflex bleeding.” This fluid can stain surfaces, including furniture and walls, and has a noticeable odor. This behavior helps differentiate them from most native ladybugs.
Bite Care and Prevention
If an Asian lady beetle bite occurs, clean the affected area thoroughly with soap and water. This removes irritants and reduces infection risk. Apply a cold compress or ice pack for 10-15 minutes to reduce minor swelling. Most bites resolve within 24-48 hours without medical intervention. If significant discomfort, spreading swelling, or signs of infection develop, such as increased redness or pus, consult a healthcare professional.
To prevent bites and avoid these insects indoors, seal potential entry points in homes. Repair damaged window screens and ensure windows and doors fit tightly. Seal cracks and openings around utility pipes, wires, and foundations with caulk or other sealants. If beetles are found indoors, gently sweep them up or use a vacuum cleaner with a stocking in the hose, as crushing them releases their staining fluid.