Pest profile

Asiatic Oak Weevil

Cyrtepistomus castaneus · Coleoptera: Curculionidae[3]

The Asiatic oak weevil is a small, greenish-gray, broad-nosed weevil from Japan that chews the edges of oak and chestnut leaves in summer and sometimes invades houses looking for a place to spend the winter.[1][2]

Asiatic oak weevil, a small greenish-gray broad-nosed weevil, on bark
Asiatic oak weevil, a small greenish-gray broad-nosed weevil, on bark. (c) Katja Schulz, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are small, 1/4 to 1/3 inch long, with a short, broad snout.[1][2]
  • They are usually greenish gray; some look reddish brown where their scales have worn off.[1][2]

Where it lives

It was first found in New Jersey in 1933 and now occurs through much of the eastern United States; it is native to Japan.[1][2]

US map: public records from 33 states since 1990 (GBIF).

Biology and life cycle

Legless grubs live on the roots of hardwood trees through fall, winter and early spring, then pupate.[1]

Adults emerge in May, are most abundant in late June and early July, and lay eggs in the soil from July into fall.[1]

Adults shelter in leaves tied together by caterpillars.[1]

Damage and signs

  • Adults feed mainly on oaks and chestnut, chewing from the leaf edge inward, sometimes leaving only the main veins; they also feed on maples, tulip poplar and other trees.[1][2]
  • Adults fed red and black oak leaves lived longer and laid more eggs than those fed white oak or sugar maple.[1]

Health risk

None; it is a nuisance when it comes indoors.[1]

Control

Pesticides

On a small, heavily infested specimen tree, most landscape insecticides should give adequate control.[1]

Common questions

What are the small gray weevils in my house?
In oak country they may be Asiatic oak weevils, which sometimes enter houses for the winter.[1]
Do Asiatic oak weevils hurt oaks?
Adults chew leaf edges, sometimes eating all but the main veins.[1]
Where did it come from?
It is native to Japan and was first found in New Jersey in 1933.[1][2]

Sources

  1. NC State Extension, “Asiatic Oak Weevil (PDIC Factsheet).” content.ces.ncsu.edu/asiatic-oak-weevil (accessed 2026-10-15)
  2. UMass Extension Landscape, Nursery and Urban Forestry Program (Landscape Insect & Mite Guide), “Cyrtepistomus castaneus (Asiatic Oak Weevil).” www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/cyrtepistomus-castaneus-0 (accessed 2026-10-15)
  3. iNaturalist, “Cyrtepistomus castaneus taxon page (order and family).” www.inaturalist.org/taxa/218048 (accessed 2026-10-06)

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