Ladybugs are often seen as beneficial insects in gardens, helping to control pests. This perception can lead to surprise when a ladybug seems to bite. While native ladybugs are generally harmless, the Asian lady beetle is known to interact with humans more directly.
Do Ladybugs Bite?
Most native ladybugs do not bite humans; their mouthparts are designed for consuming small insects like aphids, not for breaking human skin. You might feel a tickle or mild nip if a native ladybug explores your skin, but it rarely causes discomfort. Native ladybugs do not possess teeth, but mandibles strong enough to process small insects.
The species primarily responsible for bites is the Asian lady beetle (Harmonia axyridis), an invasive species introduced for pest control. These beetles are more aggressive than native ladybugs. Distinguishing features include an “M” or “W” shaped black marking behind their head. Their coloration varies from orange to red, with numerous or no spots, unlike native ladybugs which typically have consistent bright red color with defined black spots. Asian lady beetles are also slightly larger and more oval-shaped than the rounder native species.
Asian lady beetles gather in large numbers as cooler weather approaches, seeking sheltered places to overwinter. They often congregate on sunny, southwest-facing walls of buildings before entering homes through cracks. Native ladybugs, by contrast, typically overwinter outdoors under leaf litter or rocks.
Reasons for Biting and What to Expect
Asian lady beetles may bite humans, often seeking moisture or food. During dry periods or when typical food sources like aphids are scarce, they might explore human skin for moisture or nutrients. Bites can also occur if the beetle feels stressed, threatened, or trapped, such as on clothing.
A bite from an Asian lady beetle is generally a mild pinch or a sharp, momentary sting. While surprising, it rarely breaks the skin or causes bleeding. The typical reaction is a small, raised red bump, possibly with mild irritation or swelling. These reactions are usually harmless and resolve within a day or two.
Asian lady beetle bites do not transmit diseases and are not venomous. However, some individuals may experience a mild allergic reaction, including itchy eyes, nose, or rarely, respiratory symptoms. When disturbed or crushed, Asian lady beetles release a yellowish-orange, foul-smelling fluid (hemolymph) from their legs. This fluid can stain surfaces and may cause skin irritation if it contacts broken skin.
Minimizing Ladybug Encounters
To reduce indoor encounters with Asian lady beetles, preventative measures are effective. Sealing cracks and openings around windows, doors, and utility entry points is a primary step. Repairing damaged window screens and ensuring tight fits for screens and doors also helps prevent entry.
Keeping outdoor areas tidy by trimming overgrown vegetation near the home makes the property less attractive to these beetles. If Asian lady beetles enter your home, remove them gently rather than crushing them to avoid releasing their defensive, staining fluid. Vacuuming them up and immediately disposing of the sealed vacuum bag outdoors is an effective removal method.