The **European Earwig** (*Forficula auricularia*) is a common, cosmopolitan insect recognized by the pair of large, pincer-like appendages (**cerci**) at the tip of its abdomen. While they are often viewed as nuisance pests when they invade homes, earwigs are highly adaptable. They are **omnivorous**, feeding on live and decaying plant matter, as well as insects and small arthropods. In gardens, they can be both beneficial (as predators of aphids) and destructive (as pests of flowers and soft fruits).
Taxonomy and Classification
The European Earwig belongs to the family Forficulidae in the order Dermaptera (meaning “skin wings,” referring to the leathery, short forewings). They undergo **simple metamorphosis** (egg, nymph, adult). A defining feature is the presence of the cerci, which are used defensively, offensively, and in courtship. They are one of the few non-social insect species that exhibit maternal care, with the female guarding her eggs and young nymphs.
Physical Description
Adult European Earwigs are slender, reddish-brown insects, about $1/2$ to $3/4$ inch long. They have short, leathery forewings that cover about one-third of the abdomen, and hidden, semi-circular hindwings that are rarely used for flight.
The most distinctive feature is the **forceps-like cerci** at the posterior end. In **males**, these pincers are large, curved, and used for defense and combat. In **females**, the pincers are smaller, straighter, and used primarily for protection. The color and size of the cerci can be used to distinguish the sexes.
Distribution and Habitat
Native to Europe, Western Asia, and North Africa, the European Earwig has been accidentally introduced and established throughout much of North America, Australia, and South America. They require a **moist, dark, sheltered environment** and are commonly found under stones, logs, leaf litter, dense groundcover, and mulch. They invade homes through cracks and crevices when outdoor conditions become too dry or when they are seeking new harborage.
Behavior and Life Cycle
The European Earwig typically has one or two generations per year. They mate in the fall, and the female digs a small chamber in the soil to lay a clutch of 30–60 eggs. The female remains in the nest to guard the eggs, grooming them to prevent fungal growth. This **maternal care** continues after the nymphs hatch, with the mother protecting and possibly feeding the young until their second molt.
Earwigs are **nocturnal** and highly thigmotactic, meaning they prefer tight, confined spaces. During the day, they hide in crevices, often gathering in large groups inside moist hiding spots like hollow plant stems or newspapers.
Feeding and Conflict
The earwig’s omnivorous diet causes conflicts:
- **Beneficial Role:** They are valuable **predators** of slow-moving pests, notably aphids, mites, and insect eggs, acting as a natural control agent in gardens and orchards.
- **Pest Damage:** They feed on soft plant tissues, including basil, lettuce, corn silk, flower petals (especially dahlias and marigolds), and soft fruits (peaches, apricots), causing ragged holes and aesthetic damage.
- **Nuisance:** When they enter homes in large numbers, they are considered nuisance pests, though they do not cause structural damage or breed indoors.
**Note on Forceps:** The pincers are harmless to humans; they may cause a slight pinch if handled, but they are not venomous and cannot cause serious injury.
Management and Prevention
Control involves reducing outdoor harborage and setting simple traps.
- **Exclusion:** Seal all cracks, gaps, and entry points into the home, especially near ground level.
- **Habitat Reduction:** Eliminate outdoor hiding places near the foundation, such as excessive mulch layers, leaf litter, boards, and other moist debris.
- **Trapping:** Simple, non-chemical traps are highly effective. Roll up a damp newspaper, place a piece of old hose, or use a shallow container sunk into the ground and baited with vegetable oil or soy sauce; check and empty traps daily.
- **Perimeter Treatment:** If necessary, a residual insecticide can be applied to the foundation and ground immediately surrounding the home to create a barrier.
Conservation and Research
Research on European Earwigs focuses on quantifying their beneficial predatory effects versus their pest damage in agricultural systems. Growers are often advised to tolerate low populations due to their role in controlling aphids.