INSECT ENEMIES OF WESTERN FORESTS 139 



Species of Plssodes Hosts and distribution 



P. i/oscmlte Hopli. (fig. 69) Ponderosa pine, sugar pine, and western 



white pine. California, Oregon, and 

 Wasliington. 



P. californicus Hopk l*onderosa pine. California. 



P. wehhi Hopk Ponderosa pine, Mexican white pine, and 



lodgepole pine. Southern Rocky Moun- 

 tains. 



P. radiatae Hopk Monterey pine, Bishop pine, knobcone pine, 



and lodgepole pine. California and Wash- 

 ington. 



P. murrayanae Hopk Lodgepole pine. Eastern Oregon, Washing- 

 ton, and the northern Rocky Mountain 

 region. 



P. curriei Hopk Western white pine. Northern Rocky 



Mountains and northward into Canada. 



P. fasciatus Lee Douglas fir. Oregon, Washington, Idaho, and 



British Columbia. 



P. piperi Hopk Balsam firs. Oregon, Washington, Idaho, 



and British Columbia. 



P. burkei Hopk Alpine fir. Rocky Mountains. 



P. costatus Mannh Sitka spruce. Oregon to Alaska. 



P. coloradensis Hopk Spruces and w^estern white pine. Rocky 



Mountains. 



P. alascensis Hopk Engelmann spruce and probably other 



spruces. Montana and northward into 

 Alaska. 

 (Also see terminal-feeding Plssodes, p. 33.) 



PITCH MOTHS 



There are several species of moths, belonging to different families, 

 that attack the bole and larger limbs of living forest trees. Eggs are 

 laid on wounds or on the bark surface, and the caterpillars which 

 hatch therefrom mine into the inner bark and feed upon the exuda- 

 tion of pitch. These larval galleries are filled with a thick, gummy 

 pitch, and a large mass of pitch accumulates on the outsid.e of the 

 bark at the point of attack. Because of the character of their work 

 they are called pitch moths. Some species are very injurious to the 

 tops of trees, but the majority simply extend local wounds and do 

 not threaten the life of the trees. 



One large group of these pitch moths belongs to the family 

 Aegeriidae, called clear- winged moths owdng to the absence of scales 

 on the wings and the general resemblance to wasps. 



The sequoia pitch moth (Vespamima sequoia (Hy. Edw.)) (7) 

 attacks various coniferous trees throughout the Western States, in- 

 cluding pine, Douglas fir, and redwood. Although the caterpillars 

 of this moth are frequently found working in large pitchy masses on 

 wounds of forest trees, the species is not a serious enemy. Sometimes 

 breakage follows the attacks on small trees, or the pitchy, healed-over 

 galleries cause defects in the lumber. 



The adults are clear-winged moths about two-thirds of an inch in 

 length, somewhat resembling a wasp or yellow jacket, as the body is 

 markea with yellow lines. The caterpillars are dirty white or yel- 

 lowish and about three-fourths of an inch long when full grown. 



The adults appear in the latter part of June and in July and 

 lay eggs in bark crevices or in mechanical wounds on the trees. 

 The larvae start the construction of mines from the place where 

 the eggs are laid and bore winding mines through the inner bark 

 and the outer layers of wood. A large mass of gummy, sticky 

 pitch, mixed with boring dust, exudes from the point of entrance. 



