Earwigs are common insects identified by the intimidating pair of pincer-like appendages extending from their abdomen. These creatures, belonging to the order Dermaptera, are often misunderstood, leading to undue fear about their potential to harm humans. Earwigs do not bite but they can pinch, though this interaction is rarely medically significant.
The Truth About Biting and Pinching
The distinction between an earwig’s “bite” and “pinch” lies in its anatomy. A true bite involves the insect’s mandibles, or mouthparts, which earwigs rarely use defensively against humans. Their mandibles are adapted for chewing plant matter, decaying organic material, or small prey.
The structures at the rear of the earwig are called cerci, which function as forceps or pincers, not mouthparts. If an earwig is handled or feels threatened, it may flex its abdomen and use these cerci to pinch. The sensation is generally described as a mild, transient nip, similar to a snap from a rubber band.
The force generated by the cerci is insufficient to break human skin, especially in common species like the European earwig. Earwigs are not venomous and do not possess a stinger, meaning they inject no toxins when they pinch. Any minor skin irritation is a mechanical result of the pinch itself, making them harmless in a medical context.
Why Earwigs Have Pincers
The cerci serve multiple biological purposes. These appendages are primarily used for defense against smaller insect predators and for capturing prey that makes up their omnivorous diet, such as soft-bodied insects like aphids.
The cerci also play a role in wing folding. Earwigs have large, membranous hindwings that are compactly folded under small, hardened forewings, and they use their cerci to carefully tuck these wings into place after flight.
The cerci are also important in courtship and mating rituals, with differences existing between the sexes. Male earwigs possess more curved cerci, which they use to grasp the female during copulation. Female cerci are typically straighter and more narrow, sometimes providing better leverage for defense.
Debunking the Ear-Crawling Myth
The insect’s common name is the source of a persistent piece of folklore. The word “earwig” is believed to derive from Old English terms suggesting the insect would crawl into the ears of sleeping people. This myth, which sometimes included the belief that they burrowed into the brain, has been a source of anxiety for centuries.
Entomological evidence contradicts this old superstition. While earwigs seek dark, moist, and sheltered environments, the human ear canal is not a habitual destination. Earwax acts as a natural insect repellent, making the ear less appealing than the damp soil or rotting wood where they naturally reside.
Reports of any insect, including an earwig, entering a human ear are rare and accidental, typically occurring when a person sleeps outdoors. There is no scientific basis to suggest that earwigs habitually invade the human ear more than any other small insect seeking shelter.
Keeping Earwigs Out of the Home
Earwigs primarily enter homes seeking shelter when outdoor conditions become too dry, hot, or rainy. They are attracted to moisture, so prevention starts with eliminating damp hiding spots close to the foundation. This includes removing leaf litter, mulch, and decaying organic matter from the house perimeter.
To prevent indoor entry, homeowners should focus on sealing potential access points. Use caulk to fill cracks in the foundation, around utility pipes, and under basement windows. Diatomaceous earth, a non-toxic powder, can be sprinkled around entry points or in crawl spaces to dehydrate and deter the insects.
Reducing outdoor lighting near doors and windows can also help, as earwigs are nocturnal and attracted to lights. Inside the home, dehumidifiers in damp areas like basements will make the environment less hospitable. Simple traps, such as a shallow dish of soy sauce mixed with vegetable oil, can also be placed in areas of high activity.