Pest profile

Imported Longhorned Weevil

Calomycterus setarius · Coleoptera: Curculionidae[3]

The imported longhorned weevil is a small, gray-brown weevil that wanders into homes by mistake in July and August; it is harmless and doesn't damage the house, furnishings, people or pets.[1][2]

Imported longhorned weevil, a small gray-brown scaled weevil with long elbowed antennae, on a pale surface
Imported longhorned weevil, a small gray-brown scaled weevil with long elbowed antennae, on a pale surface. (c) River Ahlquist, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are about 3/16 inch long, dark-bodied and covered with grayish-brown scales; patches of missing scales look like irregular black spots.[2]
  • Seen from above and the side they have a characteristic light-bulb shape.[1]

Look-alikes

Look-alikeHow to tell them apart
Strawberry root weevilA close relative that is also a common accidental invader of homes.[1]

Where it lives

Minnesota Extension finds it mainly in southern Minnesota, and Iowa State calls it a common accidental invader in Iowa.[1][2]

US map: public records from 29 states since 1990 (GBIF).

Biology and life cycle

Larvae live in the soil and feed on small roots of aster, clover and turfgrass.[1][2]

Adults chew leaves of various annuals and perennials and are found in homes in July and August.[2]

Damage and signs

  • Root feeding by larvae causes no apparent damage, and controlling them in the soil is neither practical nor necessary.[1]

Health risk

None; they can't bite or sting and are only a nuisance.[1][2]

Control

Keep them out

Seal cracks and gaps and make sure screens and doors fit snugly to keep adults out.[1][2]

Traps and physical control

Vacuum or sweep up weevils indoors; household aerosol insecticides are not very effective, and pesticides indoors aren't necessary.[1][2]

Pesticides

When numbers are very high, a residual insecticide such as permethrin or bifenthrin around the foundation may help somewhat, though products sold to the public are not very effective against weevils.[1][2]

Common questions

What are the small gray beetles with snouts in my house?
In midsummer they are often imported longhorned weevils or strawberry root weevils wandering in from outside.[1][2]
Are these weevils harmful?
No. They don't damage the house or furnishings and can't bite or sting.[1]
Will they come back next year?
Numbers vary from year to year; a bad year doesn't mean another will follow.[2]

Sources

  1. Iowa State University Extension and Outreach (Yard and Garden), “Imported Longhorned Weevil.” yardandgarden.extension.iastate.edu/encyclopedia/imported-longhorned-weevil (accessed 2026-10-15)
  2. University of Minnesota Extension, “Home-invading weevils.” extension.umn.edu/garden-and-home/home-maintenance/household-insects/home-invading-weevils (accessed 2026-10-15)
  3. iNaturalist, “Calomycterus setarius taxon page (order and family).” www.inaturalist.org/taxa/215778 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.