Threelined larch sawfly

Threelined larch sawfly - Dorsal view of mature
larva feeding on tamarack.
  • Latin name: Anoplonyx luteipes (Cresson)
  • French name: Tenthrède trilignée
  • Order: Hymenoptera
  • Family: Tenthredinidae
Description

Distribution

Canada

The threelined larch sawfly occurs throughout northeastern British Columbia; it also occurs east to Newfoundland, north to the Yukon and south to Maine and Minnesota.

Micro-habitat(s)

Needle

Damage, symptoms and biology

The threelined larch sawfly is a common solitary defoliator. Damaging outbreaks have not been recorded in British Columbia.

Mature larva up to 15 mm long. Head, yellowish brown with black eyes. The larvae are tapered caudad with the thorax larger than the abdomen. Body, green marked with a faint middorsal pinstripe and well-defined olive green addorsal, supraspiracular, and epipleural stripes.

This species overwinters as a prepupal larva in a cocoon buried in the soil. Adults emerge in late May and the females lay eggs, usually singly, into slits cut into the needles. Larvae are present from mid-June to July. Mature larvae drop to the ground and spin cocoons in late July.

Canadian Forest Service Publications

Threelined larch sawfly

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 threelined larch sawfly is restricted to tamarack.

Main host(s)

Tamarack

Secondary host(s)

Balsam fir, black spruce, European larch, Jananese larch, juniper, Siberian larch, western larch, white spruce

Photos
  • Threelined larch sawfly Male et female cocoons (lengths: 6 and 8 mm)
  • Threelined larch sawfly Young larva, showing the three body lateral lines and brown color of head
  • Threelined larch sawfly Older larva
  • Threelined larch sawfly Dorsal view of mature larva feeding on tamarack.
  • Threelined larch sawfly
  • Threelined larch sawfly
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