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Spruce Needle Miner

Characteristics:

  • Eggs: The female deposits a group of pale-green eggs, shingle fashion, at the base of needles.
  • Larvae: Larvae are green with dark brown heads and can grow up to 8 mm long. Upon hatching, the larvae cut a hole at the base of a needle to begin eating the needles interior. Larvae eat all summer, then go dormant to overwinter inside a hollow needle.
  • Pupae: In early spring, larvae resume feeding until they are ready to pupate in mid-April.
  • Adults: Adults are smoky brown moths with blunt wings. They emerge in late May and June to mate.

Identifying infestations:

  • Clusters of dead needles enclosed by silk strands: As feeding larvae often cut off the needle they ate, which remains attached to other dead needles by silk strands.

IPM Toolkit:

  • Preventive tools:
    • Follow a regular watering, fertilizing, and pruning schedule to keep your trees as healthy as possible to resist attack.
  • Physical tools:
    • Wash away nests with a strong blast of water before bud break in spring.
    • Prune and destroy infected needles and branches where nests are located.
  • Biological tools: Not applicable.
  • Least toxic chemical tools:
    • Apply Bacillus thuringensis var. kurstaki ( also known as Organic Insect Killer, Bt.k.) according to label directions to treat infestations when larvae are young.