When a small, spotted insect resembling a ladybug lands on you, you might wonder if it bites. While true native ladybugs are generally harmless and rarely bite humans, the insect often responsible for such concerns is actually the Asian lady beetle, Harmonia axyridis. These insects, introduced to North America for pest control, can occasionally bite, particularly when seeking moisture or warmth.
Identifying the Biting “Ladybug”
The “yellow ladybug” that tends to bite is most often the Asian lady beetle, Harmonia axyridis. These beetles are oval-shaped and slightly larger than native ladybugs, measuring about 1/4 to 1/3 of an inch long. Their coloration can vary widely, from yellow and orange to red, and sometimes even black.
Asian lady beetles may have numerous spots, or very few or none at all. A distinguishing characteristic is a prominent black “M” or “W” shaped marking behind their head.
As temperatures cool in the fall, Asian lady beetles tend to gather in large numbers, seeking sheltered places to spend the winter, often congregating on buildings before moving indoors. Their biting behavior occurs when they are disturbed or if they are searching for moisture or food, especially during dry conditions or when their natural prey is scarce. If threatened or crushed, these beetles can release a foul fluid, known as hemolymph, from their leg joints, which can stain surfaces.
The Bite Sensation and Symptoms
A bite from an Asian lady beetle is described as a mild pinch or pinprick. The beetle uses its mandibles to pinch the skin, but this is not for feeding on humans. Sometimes, small spurs on their legs can also prick the skin as they move.
The physical reaction to an Asian lady beetle bite is usually minor, appearing as a small, red bump. This bump may be slightly raised and cause mild itching, but it resolves quickly. Asian lady beetle bites are not considered serious; they do not transmit diseases and are not venomous.
While severe reactions are uncommon, some individuals may experience mild allergic reactions, particularly from prolonged exposure to infestations or contact with the beetle’s hemolymph. Symptoms can include localized swelling, hives, redness, itching, or a rash. In rare instances, more pronounced allergic responses, such as itchy nose and eyes, sneezing, upper respiratory symptoms, wheezing, coughing, or an exacerbation of asthma. Anaphylaxis is rare.
Post-Bite Care and Prevention
If you experience a bite from an Asian lady beetle, clean the affected area with soap and water. This helps prevent infection. Applying a cold compress to the site can help alleviate discomfort. Medical attention is rarely necessary, but should be sought if there are signs of infection, such as increased redness, warmth, or pus, or if a severe allergic reaction occurs, indicated by symptoms like difficulty breathing or widespread swelling.
To prevent future bites and deter Asian lady beetles from entering your home, sealing entry points is an effective measure. This includes caulking cracks around windows, doors, utility pipes, and vents, and any gaps in siding or foundations. Repairing damaged window screens is also important to block their access.
If beetles are already indoors, they can be removed by vacuuming; dispose of the vacuum bag or canister contents outdoors promptly to prevent escape and avoid the release of their defensive, foul fluid. Avoiding crushing the beetles also helps prevent staining and odor. For persistent issues, consider exterior residual insecticide treatments around entry points in the fall. Handling these insects with bare hands should be avoided.