Douglas Fir: Silverspotted tiger moth

Biology

The caterpillars of the silverspotted tiger moth feed on the needles, often “tenting” branches with dirty-looking webs. Feeding occurs through fall and winter, with webs becoming more noticeable by spring. The caterpillars can reach 1 1⁄2″ in length and are mostly reddish-brown with some blue-black or yellowish hairs. Adult moths are brownish or tan with distinct silver-white spots on the wings. Minor infestations cause little harm to trees. Douglas fir is the preferred host, but the caterpillars will infest other conifers. Caterpillar hairs can cause skin irritation if they are handled without gloves.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Prune and destroy “tents” with caterpillars.
• Hand-pick (wearing gloves) individual caterpillars.

Chemical Management

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

• Apply when caterpillars first appear or when damage is noticed in late fall or early spring.
• If Bt is chosen, be sure to apply when insect is feeding. Best time is when caterpillars are young.
• Use a spreader-sticker with liquid Bt formulations.
• 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

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• Safer Brand Caterpillar Killer for Trees, Shrubs and Vegetables Concentrate II [Organic]
  Active ingredient: Bacillus thuringiensis subsp. kurstaki [EPA registration number: 70051-106-42697]
• This list may not include all products registered for this use.

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