Ladybugs, often called ladybirds or lady beetles, are widely recognized as beneficial insects, playing a crucial role in gardens by controlling common pests like aphids. Their vibrant colors and docile nature have earned them a beloved status. While generally perceived as harmless, some report experiencing what feels like a bite. This raises the question: can these gentle creatures bite?
Not All Ladybugs Bite
Most of the over 5,000 ladybug species worldwide are harmless to humans. These species are natural predators, consuming soft-bodied insects like aphids, mites, and scale insects that can damage plants. Their presence in agricultural fields and home gardens is welcomed for natural pest control. The notion of a “biting ladybug” is an exception, not a common characteristic.
Most native ladybug species do not bite humans. They possess mandibles, or chewing mouthparts, designed for consuming insect prey, but these are not strong enough to break human skin. If a native ladybug lands on a person, any sensation felt is likely a mild tickle or pinch from its legs, not a bite. Their primary defense mechanism involves secreting a foul-smelling, yellowish fluid from their leg joints when disturbed, which deters predators.
The Biting Species
The species responsible for biting humans is Harmonia axyridis, commonly known as the Asian Lady Beetle or Harlequin Ladybug. This beetle was intentionally introduced to North America from Asia in the 1960s to control agricultural pests like aphids and scale insects. However, it has since become an invasive species in many regions, often outcompeting native ladybug populations.
Identifying the Asian Lady Beetle involves several distinct visual cues. Its color can vary widely from pale orange to dark red, or even black. A key identifying feature is an “M” or “W” shaped black marking on the white area behind its head, also known as the pronotum. This marking can appear thick, thin, or broken.
Asian Lady Beetles are typically larger than native ladybugs, measuring about 1/4 to 1/3 of an inch long, and have a more oval body shape. They often gather in large clusters during the fall, seeking sheltered locations to overwinter, and are frequently found indoors.
Why They Bite and What to Expect
Asian Lady Beetles bite humans for several reasons, often related to their survival instincts. They may bite when searching for moisture or salt, especially during dry periods or when food sources are scarce. Bites can also occur as a defensive reaction if the beetle feels threatened, such as when handled or accidentally disturbed. During the overwintering period, when they aggregate indoors, they might be more prone to biting if disturbed.
A bite from an Asian Lady Beetle is typically described as a mild pinch or a pinprick sensation. While it can cause minor, short-lived discomfort, it rarely breaks the skin. These beetles do not possess venom and are not known to transmit diseases to humans. In rare cases, some individuals may experience a mild allergic reaction, such as a small, raised red bump, or irritation. If a bite occurs, washing the area with soap and water is generally sufficient.
Minimizing Ladybug Encounters
To reduce encounters with Asian Lady Beetles, especially as they seek indoor shelter during cooler months, several steps can be taken. Sealing potential entry points around your home is an effective preventative measure. This includes caulking cracks and openings around window frames, door frames, and foundations. Repairing any torn window or door screens can also prevent them from entering living spaces.
If Asian Lady Beetles make their way indoors, removing them carefully can help minimize nuisances. Using a vacuum cleaner to collect them is recommended over crushing. Crushing these beetles can cause them to release a foul-smelling, yellowish fluid, which can stain surfaces like walls, furniture, and fabrics. Avoiding direct handling of the beetles can also prevent defensive bites. Awareness of their overwintering habits and taking preventative measures in the fall can significantly reduce their presence inside homes.