WSU Extension

Hortsense

Hemlock : Coneworms
(revision date: 4/20/2015)


Biology
Coneworms attack trees by boring into green cones, shoot tips, stems, and trunks. They are particularly attracted to wound sites. Coneworm feeding results in the dieback of affected twigs. Injured twigs often can be distinguished by the presence of pitch and sawdust-like frass (excrement). These larvae are small (about 1/2" long) and light brown with a darker head. The adult coneworm is a mottled gray moth. Coneworms also attack pines, true firs, Douglas fir, and spruces.
Management Options

Non-Chemical Management
  • Remove and destroy infested twigs and cones when possible.
  • Avoid wounding trees.
  • Plant non-susceptible conifers where coneworms are a serious pest.
  • Natural enemies of the coneworm are likely.
Select non-chemical management options as your first choice!

Chemical Management

Not known to significantly damage trees. None recommended.

Images
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Caption: Coneworm on pine
Photo by: K. Grey
Caption: Coneworm damage
Photo by: L.J. du Toit