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Canadian Forest Service - National Site

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Forest pests

Larch sawfly
Pristiphora erichsonii (Htg.)

> <P class=It is not certain whether this insect is native to North America, although studies indicate the possibility of native strains. It is specific to larch, including eastern and western (tamarack) larches, and in Canada, its preferred host is tamarack. Occurring throughout the entire tamarack range, larch sawfly is considered the worst pest of tamarack in North America. Damage to trees is twofold, either initially by the female sawfly cutting slits in new shoots to deposit eggs or by the larvae feeding on needles. The larval feeding results in the greatest damage. Interestingly, the tamarack is the only conifer that is also deciduous (losing its needles in the winter). Defoliation in a given year is usually of little consequence, but repeated damage over several years will kill the tree.

Points of interest

  • one generation per year
  • first recorded outbreak in Canada was in 1878 in Bury, Quebec, and spread to Ontario, New Brunswick, and Nova Scotia over the next few years
  • male sawflies make up 2% of the population and fertilization is unnecessary since reproduction is parthenogenic
  • shrews are natural predators of this insect and were introduced into Newfoundland as a form of natural control
  • average of mature larval or full-grown length is 25 mm

References

Martineau, R. 1984. Insects Harmful to Forest Trees. Multiscience Publications Ltd., Montreal, Environment Canada, Canadian Forestry Service, Ottawa, and Supply and Services Canada, Canadian Government Publishing Centre, Ottawa. For. Tech. Rep. 32. 261 p. + x.

Rose, A.H.; Lindquist, O.H. 1992. Insects of Eastern Larch, Cedar and Juniper. Forestry Canada, Ottawa. Revised edition. For. Tech. Rep. 28. 100 p.

 

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Last updated: 2006-07-25 Top Important Notices