Asian lady beetles, also known as Harmonia axyridis, were initially introduced to control agricultural pests like aphids. While often mistaken for native ladybugs, these insects can become a nuisance, particularly when they gather in large numbers. They are known for their tendency to bite humans, a behavior that distinguishes them from most native ladybug species.
Appearance and Symptoms of Asian Lady Beetle Bites
An Asian lady beetle bite is a small, red bump on the skin. While generally not serious, the sensation is a sharp, momentary sting or a pinching feeling. This discomfort usually subsides quickly, and the bite rarely breaks the skin. For most individuals, the reaction is mild, involving slight irritation, itching, or minor swelling around the affected area.
Sometimes, the sensation might not be a true bite but rather a prick from the beetle’s small leg spurs as it explores the skin. The bites do not transmit diseases, nor do these beetles inject venom. However, some individuals might experience mild allergic reactions, especially if repeatedly exposed or if the beetle’s yellowish defensive fluid contacts the skin.
Reasons Asian Lady Beetles Bite
Asian lady beetles bite primarily as a defensive mechanism. They are not inherently aggressive insects that seek out humans to bite. Bites usually occur when a beetle feels threatened, such as when it is handled, picked up, or accidentally pressed against the skin.
In some instances, particularly during dry conditions or when seeking moisture, Asian lady beetles might bite as they investigate potential sources of water or food on the skin. This behavior can be more noticeable when large numbers of beetles congregate indoors, where the environment is often warmer and drier than their natural outdoor habitats.
Identifying the Asian Lady Beetle Itself
Asian lady beetles can be identified by several distinct physical characteristics, setting them apart from native ladybugs. These beetles are oval and convex, measuring approximately 1/4 inch (6-8 mm) in length. Their coloration varies widely, ranging from pale yellow to orange, red, and occasionally even black.
Many Asian lady beetles feature black spots on their wing covers, though the number and prominence of these spots can differ, with some individuals having very few or no spots at all. A key identifying feature is the black “M” or “W”-shaped marking on the whitish area behind their head, known as the pronotum. This marking is a reliable indicator.
Managing and Preventing Asian Lady Beetle Bites
Should an Asian lady beetle bite occur, cleaning the area with soap and water is the first step. Applying a cold compress can help alleviate any mild discomfort, swelling, or itching. Over-the-counter anti-itch creams, such as hydrocortisone, can also provide relief. Symptoms are minor and resolve quickly.
Preventing bites involves minimizing contact with the beetles. When handling them, wearing gloves can prevent direct skin exposure. To keep beetles out of homes, seal cracks and openings around windows, doors, and utility pipes, especially in late summer or early fall. Using a vacuum cleaner to remove beetles found indoors is recommended, as crushing them can release a foul-smelling, staining fluid. Seek medical attention if a bite causes severe swelling, difficulty breathing, or signs of infection like spreading redness or fever.