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Juniper Webworm

Characteristics:

  • Eggs: Eggs are white and turn to red before hatching in 9-16 days.
  • Larvae: Larvae hatch in June and begin mining the needles over summer. The larvae overwinter and re-emerge in early spring to eat new needles before pupating. Mature larvae may be up to 14 milimetres in length and have a yellowish-red body with a black head.
  • Adults: Adult moths are active in May and June. Their front wing is brown, while the front and rear margins are white. The hind wing is grey. Wingspan is about 14 millimetres. Adults live just over 2 weeks.

Identifying infestations:

  • Yellow or browning needles: Young larvae mine the plant’s needles which causes browning and defoliation. However, it’s hard to detect early infestations since the larvae are located deep within the plant’s foliage.
  • Formation of silken tubes or nests on branches: As it matures, the larvae spins a silken nest around needles it eats. By the fall, larvae feeding areas merge to form one large webbed area with dead needles.

IPM Toolkit:

  • Preventive tools: Not applicable
  • Physical tools:
    • Prune and destroy infested branches.

 

  • Biological tools: Not applicable
  • Least toxic chemical tools: Not applicable