120 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



pears to be distributed through Oregon, Idaho, Montana, and 

 Wyoming. 



Other species of Neodiprion which feed on the needles of west- 

 ern pines include the following : 



Species of Neodiprion Host and distribution 



amei'icanus banksianae Roh . Ponderosa and lodgepole pines. Idaho, Montana, 



and the Lake States. 



edwardsii (Nort.) (A2) Sugar, western white, and ponderosa pines. 



California and Oregon. 



fulviceps (Cress.) Ponderosa pine. California, Colorado, Wyoming, 



South Dakota and Nebraska. 



gillettei (Roh.) Ponderosa pine. Colorado. 



rohweri (Midd.) Pinyon and singleleaf pinyon. California, Colo- 

 rado, and New Mexico. 



The Monterey pine sawfly (Itycorsia sp.) attacks only the Mon- 

 terey pine in its native habitat, near Pacific Grove, Calif. The 

 larvae are so prevalent at times as to completely defoliate the 

 trees, either killing or seriously weakening large numbers of them. 

 The larvae are dark green or brownish, with black heads. A char- 

 acteristic of their work is that the needles are sawed off or chewed 

 into a mass, and these broken needles and brownish excrement 

 pellets are webbed together with silken threads. 



The hemlock sawfly (Neodiprion tsugae Midd.) (56) (fig. 54) 

 occasionally becomes epidemic and defoliates extensive areas of 

 western hemlock in Oregon and northward into Alaska. In British 

 Columbia and southwestern Alaska it is one of the few tree-kill- 

 ing insects. The adults are small — about % inch long. The males 

 are dark brown to black, the females larger and green to yellowish 

 brown. The larvae are green and about 1 inch long when full 

 grown. The papery cocoons are attached to the needles and to 

 debris on the ground. There is one generation a year, eggs being 

 laid in the needles from the middle of August to the end of Sep- 

 tember and the species overwintering in that stage. A few pre- 

 pupal larvae overwinter in cocoons and some even hold over a sec- 

 ond winter. Larval feeding and defoliation occur mainly through 

 July and August. These sawflies are attacked by a large number 

 of insect parasites, which normally hold the population in check. 



In the northwestern part of the United States there are two 

 native species of sawflies of the genus Anoplonyx (Platy campus) 

 that feed on the foliage of western larch. So far they have not 

 caused damage of economic importance. 



Adults of the two-lined larch sawfly (Anoplonyx occidens Ross) 

 are small, black, wasplike insects, a little less than 14 mcn long. 

 The folded wings have a blue-green metallic sheen. The larvae 

 are rather slender, about % inch long when full grown, with eight 

 pairs of prolegs on the abdomen and are brownish-green with two 

 narrow dark-green stripes along the sides, dark-brown heads, and 

 black, shiny eyes. The western larch sawfly (A. laricivorus Roh. & 

 Midd.)) closely resembles the foregoing in the adult stage, but the 

 larvae have a single green line down the center of the back. In 

 1921 an outbreak of these two insects occurred throughout the 



