Yellow-Headed Spruce Sawfly

摘要

The yellow-headed spruce sawfly, Pikonema alaskensis, can be found from Maine to Alaska in the northern United States and throughout southern Canada. It feeds on many species of spruce and is usually more of a problem on open-grown trees, such as those grown as ornamentals or in a shelterbelt. Young trees suffer more severe attacks than those that are more than 15 feet tall, and sawflies rarely attack natural forest stands. In Minnesota, the flies feed on white, black, Colorado, and Norway spruce. Of these, white spruce trees usually experience the heaviest defoliation (needle loss).