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Phantom hemlock looper

Phantom hemlock looper - Dorso-lateral and lateral views of mature larva on western hemlock
  • Latin name: Nepytia phantasmaria (Strecker)
  • French name: Arpenteuse verte de la pruche
  • Order: Lepidoptera
  • Family: Geometridae


British Columbia



Damage, symptoms and biology

The phantom hemlock looper is a common and occasionally destructive solitary defoliator.

Severe defoliation may result in reduced increment, top-kill and tree mortality.

Mature larva to 28 mm long. Head, green with ten prominent black spots. Dorsum yellowish green with a faint green middorsal stripe; subdorsal stripes white edged on either side with a fine dark green line; supraspiracular area green with a pair of wavy, broken dark lines; yellow spiracular stripe.

This species overwinters in the egg stage. Larvae emerge in late May and initially feed on new foliage. Mid- to late-instar larvae prefer to feed on older foliage. Pupation occurs on foliage in August, adults emerge in September and October and lay up to 115 eggs singly or in small groups on undersides of needles.

Life cycle (West of the Rockies)

Life cycle (West of the Rockies)
Stage/Month J F M A M J J A S O N D

Other information

In British Columbia, localized short-lived outbreaks have been recorded in municipal parks at Burnaby, New Westminster and Hope in 1956-57 and 1994 as well as in the natural forest near Coquitlam Lake in 1982 and near Port Mellon in 2001.

Canadian Forest Service Publications

Phantom hemlock looper

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)

Main host(s)

Amabilis fir, grand fir, Rocky Mountain Douglas-fir, Sitka spruce, western hemlock, western redcedar


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