Ministry of Forests Branches Search the Forest Practices Branch Web Site Send a Note to the Forest Practices Branch Contact Information for the Forest Practices Branch
to index

Larch sawfly, Pristiphora erichsonii
 

 
Fig. 21  
Maturing larch sawfly larvae. Gregarious feeding is common. 		Fig. 22 
Tip curl is an early symptom of larch		 Fig. 23 
Severely defoliated larch due to larch sawfly infestation.

Distribution:  On western larch in the east Kootenays and throughout the range of eastern larch (tamarack) in northern B.C.

Tree Species Attacked: All ages of western larch and eastern larch are attacked

Insect Description & Damage Symptoms: Young larvae have cream-coloured bodies and brown heads. As they mature, their bodies become greenish and eventually grey-green on top and whitish underneath. The heads darken to become shiny black. Full-grown larvae reach 2.0 cm in length, and may be seen holding on with their forelegs and arching their back with their posterior end over the head.

Eggs are laid in slits in terminal shoots and twigs in June or July. Larvae emerge from the slits shortly thereafter and feed in groups, stripping the foliage as they move down the branch. Terminal shoots and twigs are damaged during egg-laying and may be left curled and distorted for several years. The larvae drop to the litter layer and spin paper-like, capsule-shaped, brown cocoons to spend the winter. They pupate in early spring.

Damage:  Larch are very tolerant of defoliation; therefore, no reports of direct tree mortality on western or eastern larch have resulted from larch sawfly attack in British Columbia. Growth reduction and branch mortality may, however, occur following outbreaks. Outbreaks may cover thousands of hectares.

Similar Damage: Light defoliation may be confused with bud moth, larch needle cast, larch needle blight, or larch casebearer damage. Close examination will reveal distinct differences

Back to the Pest Field Guide Index

Contact Tim Ebata if you have comments on the presentation of this information.

BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated March 04, 2002