Damage, symptoms and biologyBeginning 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)
Other informationThe 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
Diet and feeding behaviour
: Feeds on the leaves of plants.
- Free-living defoliator: Feeds on and moves about freely on foliage.
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