Pest profile

Winter Moth

Operophtera brumata · Lepidoptera: Geometridae[2]

The winter moth is an invasive European moth whose pale green inchworms feed on buds, blooms, leaves and fruit from March to midsummer; it reached the Pacific Northwest in 1958.[1]

Winter moth male, a small moth with light brown, finely patterned wings, on wood
Winter moth male, a small moth with light brown, finely patterned wings, on wood. (c) SteveM4560, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Larvae are pale green inchworms with a light stripe down each side, up to 12 mm long.[1]
  • Males are small moths with light brown to tan, hairy-looking wings; females have reduced wings and can't fly.[1]
  • Larvae tie leaves together with silk but don't roll them the way leafrollers do.[1]

Look-alikes

Look-alikeHow to tell them apart
LeafrollersLeafroller larvae roll leaves; winter moth larvae only tie them together with silk.[1]

Where it lives

Introduced from Europe, it was found in the Pacific Northwest in 1958.[1]

US map: public records from 7 states since 1990 (GBIF).

Biology and life cycle

It pupates in the soil in summer and fall, and adults emerge in late fall and early winter, after the first frost.[1]

The flightless female mates, crawls up the plant and lays eggs in bud or bark crevices; larvae hatch in early spring and feed on opening buds.[1]

After several weeks, larvae drop to the soil on silk threads to pupate; there's one generation a year.[1]

Young larvae spin fine silk threads to drift on the wind to new plants; the threads can be seen in slanting morning and evening light.[1]

Damage and signs

  • Larvae damage buds, blooms, leaves and fruit from March to midsummer.[1]

Health risk

It feeds on plants; the PNW Insect Management Handbook mentions no risk to people.[1]

Control

Prevention

Check plants in early spring for larvae, webbing and feeding on buds.[1]

Traps and physical control

Home gardeners can pick larvae off when found and prune out infested growth.[1]

Biological control

Lacewings, assassin bugs and spiders eat the larvae but don't regulate populations well; cold winters matter more.[1]

Pesticides

The PNW handbook's blueberry page lists no products registered for home-garden control.[1]

Common questions

What green inchworms are eating my blueberry buds in spring?
Likely winter moth larvae, pale green inchworms that feed on buds, blooms, leaves and fruit.[1]
Why is it called the winter moth?
The adults emerge in late fall and early winter, after the first frost.[1]

Sources

  1. Pacific Northwest Pest Management Handbooks (OSU, WSU, University of Idaho), “Blueberry: Winter moth (Insect Management Handbook).” pnwhandbooks.org/insect/small-fruit/blueberry/blueberry-winter-moth (accessed 2026-10-06)
  2. iNaturalist, “Operophtera brumata taxon page (order and family).” www.inaturalist.org/taxa/60780 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.