PestMedium Severity

Douglas Fir Cone Moth

Barbara colfaxiana

A moth whose larvae infest Douglas fir cones, potentially destroying seed crops. Adults are silvery gray moths about 1/2 inch long, and larvae create resinous tunnels through cone bracts, feeding on scales and seeds, which can prevent cone opening and seed release.

Peak Season: Adult flight: Early spring (April-May)Egg laying: May to early June on young conesLarval feeding: 2 months during cone developmentPupation: July-AugustOverwintering: As pupae in resin-coated cocoonsVulnerability period: During heavy cone crop years
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Douglas fir cone moth showing adult moth and larval damage to cone scales

Identification & Symptoms

What to Look For

Resinous exudations between cone scales
Misshapen or distorted cones
Frass accumulation on cone surfaces
Heavily infested cones withering before maturity
Cones failing to open to release seeds
Visible larvae tunnels through cone bracts

Potential Damage

Destruction of seed crops in Douglas fir stands
Prevention of natural regeneration
Economic losses in seed orchard operations
Reduced cone viability and seed production
Impedance of cone opening mechanisms

Lifecycle

Adults emerge in April-May following spring temperatures. Eggs are deposited on protruding bracts of young cones in May to early June. Larvae bore through bracts creating resinous tunnels, feeding first on scales then seeds for about 2 months. Pupation occurs in July-August. One generation annually with some pupae remaining dormant for biennial cycles.

Professional Treatment Approach

1

Imicide applications during adult flight periods in early spring

2

Timing treatments with cone development stages

3

Address stress factors: poor sites, drought, nutritional deficiencies

4

Monitor for adult emergence in April-May

5

Remove and destroy heavily infested cones when feasible

Recommended Mauget Products

Imicide

Professional-grade treatment specifically effective against douglas fir cone moth.

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