Asian lady beetles are common insects often confused with native ladybugs, and their increasing presence, particularly indoors, frequently raises questions about their potential to bite. These beetles, scientifically known as Harmonia axyridis, are a familiar sight in many regions.
The Biting Behavior of Asian Lady Beetles
Asian lady beetles can bite, though it’s more a nip or pinch. This sensation is minor, feeling like a pinprick, and is an annoyance rather than causing significant pain. They often nip when landing on skin, handled, or if food sources are scarce. Their chewing mouthparts evaluate surfaces, sometimes causing this pinch.
Bites from Asian lady beetles are not serious and do not transmit diseases. Direct injury from a bite is minimal, causing minor discomfort that quickly subsides. Rarely, exposure to these beetles, especially dead ones, can cause allergic reactions like eye irritation, hives, or asthma in sensitive individuals. When disturbed or crushed, they may release a foul-smelling, yellowish fluid, a defensive mechanism that can stain surfaces.
Identifying Asian Lady Beetles
Distinguishing Asian lady beetles from native ladybugs involves several key physical characteristics. Asian lady beetles are oval and convex, measuring about 1/4 inch long, slightly larger than many native ladybugs. Their coloration varies widely, ranging from orange to red, yellow, or even black. While some have numerous black spots, others may have fewer, indistinct, or no spots at all.
A definitive identifying feature is the distinct “M” or “W” shaped black marking located on the whitish area behind their head, known as the pronotum. This marking helps differentiate them from native ladybugs, which lack this specific pattern. Asian lady beetles tend to aggregate in large numbers on and within buildings, especially during cooler months as they seek overwintering sites. This habit often leads to their presence indoors, unlike most native ladybugs that prefer to overwinter outdoors.
Managing Encounters and Bites
When Asian lady beetles enter homes, the easiest way to remove them is by using a vacuum cleaner. Using a vacuum with a bag or a nylon stocking inside the hose allows easy outdoor disposal, as crushing them releases a staining, odorous fluid. Sweeping them into a dustpan is another option for removal.
Preventative measures reduce indoor encounters. Sealing cracks around windows, doors, utility pipes, and fascia boards with caulk blocks entry points. Repairing damaged window screens and installing screening behind attic vents also prevents entry. If a nip occurs, washing the affected area with soap and water is sufficient, as the reaction is minor and temporary. If a suspected allergic reaction develops, consulting a physician is recommended.