Birch sawfly

Birch sawfly - Colony of young larvae on a white birch leaf
  • Latin name: Arge pectoralis (Leach)
  • French name: Tenthrède du bouleau
  • Order: Hymenoptera
  • Family: Argidae
Description

Distribution

Canada

Micro-habitat(s)

Leaf

Damage, symptoms and biology

Beginning in June, the female, which is wasp-like with silvery membranous wings, cuts a network of slits along leaf margins and deposits her eggs in them. In July, groups of larvae can be readily observed around the leaves, which they consume right down to the midrib. At the end of its larval development, the insect falls to the ground and weaves a silky cocoon in which it overwinters as a prepupa in the litter.

Life cycle (East of the Rockies)

Life cycle (East of the Rockies)
Stage/Month J F M A M J J A S O N D
Egg
 
Larva
 
Cocoon
 
 
Adult
 

Other information

The birch sawfly has only one generation per year. This species has at times caused serious defoliation of birch in Nova Scotia and in British Columbia. In Quebec, infestations have been very localized and sporadic.

No intervention is required because the infestations are short-lived.

Canadian Forest Service Publications

Birch 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)

Main host(s)

Grey birch, white birch, yellow birch

Photos
  • Birch sawfly Pinned adult, wings spread out
  • Birch sawfly Colony of young larvae on a white birch leaf
  • Birch sawfly Mature larva feeding on a white birch leaf
  • Birch sawfly Cocoons on white birch leaves
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