Many sawflies feed on conifers.
They generally occur in groups and can cause serious defoliation. Different species are active at different times of the year. Sawfly larvae resemble the caterpillars of moths and butterflies in body form but a closer look can easily determine the difference. Differentiating sawflies from other caterpillars is important in that a biological insecticide that works well against butterfly and moth larvae is not effective against sawflies. The introduced pine sawfly was first detected in the Commonwealth in 1992.