Earwigs in Missouri: Why They Come Inside and How to Control Them

Earwigs are one of the more alarming-looking insects Missouri homeowners encounter — the distinctive pincers at the tail end of their body create an intimidating impression that far exceeds their actual threat. They are harmless, common, and primarily outdoor insects that enter homes under specific conditions. Here is what you need to know.

Identifying Earwigs

Missouri's most common earwig is the European earwig (Forficula auricularia), an introduced species now widespread throughout the state:

• Elongated, flattened body, dark brown to reddish-brown
• Distinctive forceps (cerci) at the tail end — curved in males, straighter in females
• Body length approximately 12–15mm for adults
• Short, leathery fore wings that cover the folded hind wings
• Move quickly when disturbed

The name "earwig" comes from a European folk belief that they crawl into sleeping people's ears — there is no basis for this. Earwigs do not seek out ears, do not parasitize humans, and the pincers, while they can pinch skin if handled, are not strong enough to cause injury. They are completely harmless to people.

Earwig Biology and Outdoor Habits

Earwigs are omnivores that feed on decaying plant material, living plants, and other small insects. They are nocturnal, strongly thigmotactic (they seek tight spaces in contact with surfaces on multiple sides), and require moisture. Outdoors, they live under mulch, rocks, bark, and dense plant debris close to the soil. They are actually beneficial in gardens — they eat aphids and other garden pests in addition to plant material.

Female earwigs are notable for their maternal behavior — they lay eggs in underground chambers and actively tend them, which is unusual among insects.

Why They Come Inside Missouri Homes

Earwigs enter homes primarily in response to two conditions: drought (seeking moisture) and fall cooling (seeking warmth). Missouri's periodic summer dry spells drive earwigs from dried-out mulch beds toward moisture inside structures. The fall cooling pattern that drives stink bugs and boxelder bugs indoors also affects earwigs, though to a lesser degree.

Entry is almost always at ground level — through gaps under doors, around utility penetrations, through cracks in the foundation. Earwigs found indoors typically are in basements, bathrooms, and kitchens — the most humid areas of the home.

Control: Addressing the Exterior Habitat

Indoor earwig problems are almost always sourced from outdoor populations immediately adjacent to the structure. The most effective control addresses the outdoor habitat:

• Remove mulch from direct foundation contact: Earwigs concentrate in mulch beds adjacent to the foundation. Pulling mulch back 6 to 12 inches from the foundation creates a dry buffer zone that earwigs are reluctant to cross.
• Reduce moisture near the foundation: Fix drainage issues, redirect downspouts, and ensure the grade slopes away from the house
• Remove leaf debris and plant material: Keep the foundation perimeter clear of organic debris where earwigs live
• Seal entry points: Door sweeps, caulk around utility penetrations, and foundation crack sealing reduce entry
• Exterior perimeter treatment: Professional residual treatment along the foundation kills earwigs before they enter and reduces the population in the immediately adjacent outdoor habitat
• Reduce outdoor lighting: Exterior lights attract the insects earwigs feed on — reducing attraction of prey reduces earwig presence near the structure

Earwig invasions are almost entirely addressed by exterior treatment and habitat modification. Interior-only treatment without addressing the outdoor source provides only temporary relief.