Henri Goulet. 1998. Sawflies (Hymenoptera: Symphyta) in Smith, I.M., and G.G.E. Scudder, eds. Assessment of species diversity in the Montane Cordillera Ecozone. Burlington: Ecological Monitoring and Assessment Network, 1998.

SAWFLIES
(HYMENOPTERA: SYMPHYTA)

Henri Goulet

SUMMARY

The Symphyta Fauna in the Montane Cordillera Ecozone is moderately diverse in species (254 species recorded) and in genera (69 out of 119 Canadian genera). Most of the species are native (95%) with ranges spanning most of Canada and commonly restricted from the Rockies to the Pacific. About 17% of the fauna is found nowhere else in Canada.

Most of the species consume plant tissue (usually leaves) as larvae, and therefore, many species have an important economic impact in agricultural, forest, and the ornamental industries. Some species are beneficial as they contribute to the control of noxious weeds. As adults, the economic impact is minimal except for the markedly predatory adults of the genus Tenthredo.

Within this fauna two groups stand out: the native and the introduced species. The introduced species are little diverse (5% of the species), cause some damages to the Canadian agriculture, especially in small fruits. These species are mainly encountered in manmade habitats, but in the ecozone they do not seem to dominate. Most of the native species have mainly no economic impact, but some species are important defoliators of forest or ornamental trees. These species are mainly encountered in natural habitats. The origin of the native fauna is mainly from a south to north movement following the ice retreat and the climatic improvements. In addition, there were invasions of boreal species from east of the Rockies and of coastal species from the southwest along the cascades or low mountain passes through the coastal ranges. The origin of the alien fauna is mainly since colonial times from major Pacific coast ports, and partly from the nursery trade especially following the Second World War. Introductions are still discovered on the Pacific coast despite excellent quarantine efforts. Some of these new arrivals are likely to expand into the ecozone

Populations of most sawfly species seem generally stable.