Filbert: Filbertworm

categories: Filbert Filbert Insects Tree Fruits

last review date: 2025-09-14 10:38

Biology

The filbertworm is the larval stage of a gray to reddish moth. The adult moth has copper- to gold-colored bands across the forewings and a wingspread of approximately 1⁄2″. The female moth lays eggs on or near the developing nut.

Emerging caterpillars bore into the nut through the base of the husk. The caterpillars feed inside the nut, blackening and destroying the kernel. Mature caterpillars are pinkish to white and 1⁄2″ to 3⁄4″ long. They feed for three or four weeks before dropping to the ground to pupate.

Management Options

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

Non-chemical Management

Select non-chemical management options as your first choice!

• Harvest nuts as early as possible. Dry nuts immediately after harvest to minimize damage.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Apply in early July and again three weeks later.
• NOTE: Esfenvalerate is toxic to bees.
• Do not apply products containing esfenvalerate on or near blooming plants.
• To minimize risk to bees, apply in the evening after bees have stopped foraging for the day.
• Homeowners should not make foliar applications to trees over 10 ft. tall.
• Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

Examples of pesticides that are legal for home use in Washington State are listed below.
The list may not include all products registered for this use.

• Bug Buster-O [Organic]
  Active ingredient: pyrethrins (EPA reg. 1021-1771-54705)
• Monterey Bug Buster II
  Active ingredient: esfenvalerate (EPA reg. 1021-1778-54705)