Spruce needleminer
Coleotechnites piceaella
16 host plants
Last updated
Spruce needleminer larvae create serpentine, yellowish-tan mines within the needles of spruce trees, often starting in spring as needles expand. Infested needles eventually brown and are shed by midsummer. Picea species including Engelmann spruce and blue spruce show damage. Fine webbing may appear on the shoots of heavily infested trees. Damage is primarily cosmetic but detracts from landscape appearance.
Needle miners have numerous parasitoid wasps that naturally suppress populations. Prune and remove affected twigs before adult emergence in early spring. Since damage is cosmetic, no chemical control is warranted in most landscapes. Maintaining tree vigor through proper irrigation and avoiding drought stress supports natural enemy activity and reduces severity.
Quick Reference
Spruce needleminer Emergence (est.) typically begins around 870 GDD₃₂. As of April 3, 2026, all seven Puget Sound stations have passed this threshold (1070–1180.6 GDD₃₂), so Emergence (est.) is likely underway across the lowlands.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,181 | Emergence (est.) | — | — |
| Seattle / UW | 1,171 | Emergence (est.) | — | — |
| Kent / Auburn | 1,111 | Emergence (est.) | — | — |
| Olympia / Tumwater | 1,106 | Emergence (est.) | — | — |
| Bellingham / Whatcom | 1,101 | Emergence (est.) | — | — |
| Tacoma / Puyallup | 1,075 | Emergence (est.) | — | — |
| Sequim / Rain Shadow | 1,070 | Emergence (est.) | — | — |
Source: MSU Extension. First larval activity after egg hatch for Coleotechnites piceaella. Added 2026-04-03. About GDD₃₂ →
Cultural Controls
- Natural predators may help control needleminer populations.
- Hand-pick larvae on small trees.
- Plant resistant species.