Beetles represent an incredibly diverse and abundant group of insects, with over 400,000 described species across the globe. These creatures inhabit nearly every terrestrial and freshwater environment, displaying a wide range of sizes, shapes, and behaviors. Given their widespread presence, it is natural for people to wonder about potential interactions with them, especially concerning whether these insects can inflict bites.
Do Beetles Bite Humans?
While beetles possess chewing mouthparts, most species do not bite humans or lack the physical capability to cause significant harm. Many beetles use their mandibles for feeding on plants, other insects, or decaying matter, not for attacking larger animals. A beetle typically resorts to biting or pinching only as a defensive measure when threatened, is handled, or is accidentally trapped against the skin.
These defensive actions are not acts of aggression but rather a response to perceived danger. For instance, if a beetle crawls on a person and gets squeezed, it might instinctively pinch or bite. Some beetles, particularly those with larger mandibles, are more likely to deliver a noticeable pinch than a true bite that breaks the skin.
Understanding Beetle Bites and Their Effects
Although most beetles are harmless, certain species can cause irritation or discomfort. Blister beetles, for example, do not bite or sting but release cantharidin when disturbed or crushed. This substance causes a skin reaction known as blister beetle dermatitis. Contact with cantharidin leads to localized pain, burning, redness, and swelling, forming fluid-filled blisters within 24 to 48 hours. These blisters are painful, generally not life-threatening, and typically resolve within about a week with a low risk of scarring.
Stag beetles, particularly females, possess robust mandibles capable of delivering a painful pinch if provoked. While male stag beetles have intimidating, antler-like jaws, they often lack the strength to break human skin, whereas the smaller mandibles of females can exert more force. The strong, grappling-hook-like legs of stag beetles can sometimes cause more discomfort than their mandibles when they cling to the skin. Longhorned beetles can also inflict a painful bite that may cause discomfort for one to two days.
Other beetles, like some ground beetles, might pinch, but this is rarely painful or harmful. Certain ground beetle species can also secrete foul-smelling fluids that may cause skin irritation. Carpet beetles do not bite humans; however, their larvae have tiny, hair-like bristles that can cause an allergic reaction, leading to itchy, red bumps or rashes.
For minor irritations or bites, first aid involves washing the affected area with soap and water. Applying a cold compress or ice pack can help reduce swelling and discomfort. Over-the-counter topical creams, such as hydrocortisone or calamine lotion, or oral antihistamines, can relieve itching and inflammation.
Medical attention is recommended if symptoms worsen, if there are signs of infection (increasing redness, warmth, pain, or pus), or if a severe allergic reaction occurs. Signs of a severe reaction include difficulty breathing, swelling of the lips, face, or throat, dizziness, or a rapid heart rate. If cantharidin from a blister beetle comes into contact with the eyes, it can cause “Nairobi eye,” requiring consultation with an eye doctor.