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Hydriomena irata Swett

  • Latin name: Hydriomena irata Swett
  • French name:
  • Order: Lepidoptera
  • Family: Geometridae


British Columbia

This species is generally distributed throughout British Columbia south of 55o latitude; it also occurs south to California.



Damage, symptoms and biology

Hydriomena irata is a common innocuous solitary defoliator.

Mature larva up to 20 mm long. Head, dark with cream coloured herringbone pattern on each lobe. Body, cream coloured with grey mottle; dark middorsal + marking on dorsum of each abdominal segment.

This species overwinters as a mid-instar larva. Larval feeding resumes in the spring and continues until early June. Pupation occurs in June, adults emerge from late June to July, mate and lay eggs. The eggs hatch soon after and the larvae feed until the onset of cooler conditions.

Canadian Forest Service Publications

Diet and feeding behaviour

  • Phyllophagous : Feeds on the leaves of plants.
    • Free-living defoliator: Feeds on and moves about freely on foliage.
Information on host(s)

The principal hosts of Hydriomena irata are Douglas-fir, western hemlock and Sitka spruce; other hosts include amabilis fir, grand fir, subalpine fir, mountain hemlock, Engelmann spruce and white spruce.

Main host(s)

Amabilis fir, red alder, Rocky Mountain Douglas-fir, Sitka spruce, western hemlock

Secondary host(s)

Douglas-fir, eastern hemlock, Engelmann spruce, Garry oak, grand fir, lodgepole pine, mountain alder, mountain hemlock, subalpine fir, western redcedar, white spruce


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