Earwig Facts, Identification and Control
Scientific Order: Dermaptera
Forficulidae, including the most common earwig, the European Earwig (Forficula auricularia)
Size: Around 16 millimeters long (or ⅝ inches)
Color: Red-brown to dark brown with brighter, yellow-brown legs.
Most species of earwig are omnivorous. They eat a wide variety of living and dead plant and animal material, including flowers, bushes, and hostas.
Earwigs are considered a crop pest because they feed on seedlings, corn silk and ears, cauliflower heads, chard, and several other varieties of flowering crop plants. Healthy, adult crops will usually survive the feeding, but earwigs may kill young or developing crops.
Despite their crop-feeding propensities, earwigs also hunt and kill other, often more damaging crop pests, such as aphids, scale insects, midges, and caterpillars. Some species of earwig are exclusively carnivorous.
Earwigs are nocturnal and sensitive to heat and dryness. They hide in dark, damp locations during the day and only become active at night. In dry environments or during hot seasons, earwigs have to seek out confined, dark, and wet locations, such as the inside of plant life or under potted plants, in order to survive.
Earwigs only fly very rarely and can’t fly for very long or over long distances. When they do use their wings, it’s generally to “hop” from one location to another. An earwig will generally climb to an elevated object in order to get height before flying.
Earwigs don’t directly damage property, though they leave droppings wherever they go and secrete a foul-smelling liquid from their abdomens when threatened or killed.
Earwigs may leave ring-shaped holes behind in leaves and flowers they’ve fed on, but they don’t inflict significant damage on adult plants. Earwigs are considered a nuisance in buildings primarily for sanitary reasons.
Earwigs don’t reproduce indoors or permanently infest dwellings, but they may temporarily migrate into buildings during the summer to escape the heat in high numbers.
Adult earwigs reproduce sexually in the late summer to early fall. A fertilized female earwig excavates a special burrow 15mm deep, which she uses to store fertilized eggs. The female deposits 20-60 eggs in the burrow and stands watch over them for however long hatching takes, which can be anywhere between 12 to 85 days depending on temperature. Earwig eggs measure 1.13 mm in length and .85 mm in width at first, and swell to almost double that size by the time they hatch.
Earwigs undergo four nymphal “instar” stages broken into two phases: nesting and free-foraging. First instar nymphs stay in the nest under their mother’s protection until they molt out of their birth exoskeleton. Second instar nymphs venture out of the nest at night to seek food. Third and fourth instar nymphs become free-roaming, seeking food and shelter on the surface until adulthood.
Earwig nymphs generally resemble smaller adults, though first instar nymphs are clear and much smaller. The main physical difference between instar stages is an increasing number of antennal segments, gradually developing wings, and growing cerci.
Earwigs have a large set of forceps-like pincers called a cerci located on the tip of their abdomens (rear, opposite their heads). Female cerci are relatively straight, while male cerci curve and resemble a beetle’s pincers. Earwigs use their cerci to hunt for food and defend themselves.
Most earwigs, including the European earwig, possess two sets of wings and are capable of limited flight. The longer, thin hind wings used to fly fold out from under short, hard, and leathery forewing covers called “tegmina”. The tegmina protect the earwigs’ hind wings when they’re not in use, and open to allow the hind wings to quickly spread when the earwig flies.
The common belief that the name “earwigs” comes from the insect’s habit of crawling into human ears is a myth. There is no evidence to suggest that earwigs purposefully crawl into people’s ears. Instead, the name may come from the shape of the insect’s unique hind wings, which resemble the shape of a human ear when unfolded in flight.
Adult earwigs use their pincers defensively and will clamp down on humans if threatened, but they can’t generate enough force to hurt people. Earwigs should be considered a nuisance and possibly a crop pest, but they are not dangerous.
Signs of Infestation
Earwigs don’t permanently infest indoor locations, but they’re commonly found in large numbers in dark, damp, enclosed areas. The soil beneath decks and porches is a perfect nesting ground for earwigs. If you’ve seen earwigs around or in your building, start by checking beneath your deck, especially at night.
If you have a garden or ornamental plants, look for small bite marks on the leaves or flower buds. These bite marks may be circular on the inner part of a leaf or flower bud, or they may simply look like fraying on the outer edges.
Look for earwigs under loose floorboards, especially in damp or dark locations like basements and attics. Unfinished basements can sometimes attract earwigs. Maintenance problems like rotting or damaged wood, plumbing leaks, or cracks in window frames can also invite earwigs.
Earwigs secrete a foul-smelling liquid when threatened or crushed, so if you have an unidentified smell outside or around your building, look for earwigs. The secreted liquid can also stain cloth and carpeting if left alone.
Treatment and Prevention
Practice regular lawn, yard, and lot maintenance. Reduce the natural debris earwigs can hide under to deprive them of places to stay out of the heat. Remove rotting or dying plants, fallen leaves, piles of lumber, and excess mulch. Look for ways to reduce the humidity around your building
Minimize moisture and humidity in and outside of your building. Make sure your plumbing isn’t leaking and your yard doesn’t have low patches that retain water. Consider using a dehumidifier in basements and attics. Keep an eye on your downspouts, gutters, and other irrigation systems to prevent water buildup after rain. Ventilate crawl spaces properly. Look for sources of moisture inside your building and correct them.
Earwigs don’t permanently infest homes, so simply sweeping or vacuuming up earwigs could be effective, as long as you can identify how they got in and make sure they can’t just get in again. Look for cracks and gaps in the foundation, around utility lines and window frames, and in the siding, insulation, and roofing. Caulk or otherwise seal off openings like these. Replace damaged screens and weatherstripping.
University of Minnesota Field School for Agricultural Professionals’ European earwigs in homes and gardens fact sheet
bugguide.net Earwigs Identification, Images, & Information entry
Iowa State University Horticulture and Home Pest News Earwig Encyclopedia entry
University of Florida Department of Entomology & Nematology European earwig “featured creatures” spotlight
Penn State University College of Agricultural Sciences Department of Entomology’s European Earwigs Insect Advice Fact Sheet
Cornell University Department of Entomology Earwig Insect Diagnostic Laboratory fact sheet
University of California Agriculture & Natural Resources Statewide Integrated Pest Management Program’s “How to Manage Pests” Earwigs Section
Australia Commonwealth Scientific and Industrial Research Organisation’s Entomology Dermaptera: earwigs database entry