WSU Extension

Hortsense

Spruce
 
Disease
Oil discoloration of foliage 
Rhizosphaera needle cast 
Rust 
Insect
Coneworms 
Cooley spruce gall adelgid 
Douglas fir tussock moth 
Pine needle scale 
Spruce aphid 
Spruce bud scale 
Spruce budworm 
Spruce needleminer 
Spruce spider mite 
White pine weevil 



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Caption: Spruce needleminer larva
Photo by: R. Van Denburgh
  
Spruce : Spruce needleminer
(revision date: 4/20/2015)


Biology
The spruce needle miner feeds on spruce needles from the inside out, starting at the base of the needle. These larvae are light greenish to brown and grow to approximately 1/2" long. Large amounts of webbing are deposited around the needles. Completely mined needles may be cut off, sometimes resulting in severe needle loss. The spruce needleminer attacks mainly blue, Sitka, and Engelmann spruce in the western U.S. The adult is a small brown moth.
Management Options


Non-Chemical Management
  • Natural predators may help control needleminer populations.
  • Hand-pick larvae on small trees.
  • Plant resistant species.
Select non-chemical management options as your first choice!

Chemical Management

Apply late May or early June when moths and young larvae appear. Horticultural oils, soap-based products and some other products may cause discoloration of spruce needles, particularly on Colorado blue spruce. Read labels carefully and test on a small area before application. 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • This list may not include all products registered for this use.
Images

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Caption: Spruce needleminer larva
Photo by: R. Van Denburgh