Pest profile

Filbertworm

Cydia latiferreana · Lepidoptera: Tortricidae[2]

The filbertworm is a moth whose larvae bore into hazelnuts, chestnuts and acorns and destroy the kernel; it's the key hazelnut pest in the Pacific Northwest.[1]

Filbertworm moth, reddish with bands of golden scales across the forewings
Filbertworm moth, reddish with bands of golden scales across the forewings. (c) Ken-ichi Ueda, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adult moths are gray to reddish with golden bands of scales across each forewing.[1]
  • Grown larvae are whitish with a brown or black head and about 1/2 inch long.[1]
  • Infested nuts hold only frass and mold where the kernel should be.[1]

Look-alikes

Look-alikeHow to tell them apart
Codling mothA close relative; filbertworm adults are gray to reddish with golden bands across each forewing.[1]

Where it lives

It's found with many wild and cultivated fruits and nuts in North America and is common in acorns and chinkapin in the Pacific Northwest; in California it can hit pomegranates.[1]

US map: public records from 42 states since 1990 (GBIF).

Biology and life cycle

Mature larvae overwinter in silk cocoons under leaves and debris, up to 2 inches deep in soil, or in bark cracks.[1]

Moths fly from late May through October, and there are two generations a year.[1]

Females lay eggs on the upper surface of leaves.[1]

Damage and signs

  • Early feeding on young nut clusters can make nuts abort, and later larvae infest nuts and destroy the kernel.[1]

Health risk

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

Control

Prevention

Hazelnut varieties differ; those with thicker shells at the basal scar, such as 'Lewis', 'Jefferson', 'Dorris' and 'Barcelona', are less susceptible.[1]

Sanitation

The first nuts to drop are more often infested; removing them, and fallen acorns from nearby oaks, can reduce pressure.[1]

Biological control

Predators, parasitic wasps such as Trichogramma minutum, and bats kill eggs, larvae and moths.[1]

Pesticides

Home-use options listed include spinosad, carbaryl, esfenvalerate and neem-based products; pheromone traps help time sprays.[1]

Common questions

What hollowed out my hazelnuts?
Likely filbertworm larvae, which bore into the nut and destroy the kernel.[1]
Do filbertworms live in acorns too?
Yes. They're particularly common in acorns and chinkapin in the Pacific Northwest.[1]

Sources

  1. Pacific Northwest Pest Management Handbooks (OSU, WSU, University of Idaho), “Hazelnut: Filbertworm (Insect Management Handbook).” pnwhandbooks.org/insect/nut/hazelnut/hazelnut-filbertworm (accessed 2026-10-06)
  2. iNaturalist, “Cydia latiferreana taxon page (order and family).” www.inaturalist.org/taxa/148907 (accessed 2026-10-06)

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