Birch sawfly

Colony of young larvae on a white birch leaf Thérèse Arcand

French common name: Tenthrède du bouleau
Scientific name: Arge pectoralis (Leach)
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Argidae

Distribution

Canada

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.

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.