INSECT ENEMIES OF WESTERN FORESTS 139 
Species of Pissodes Hosts and distribution 
P. yosemite Hopk. (fig. 69) _______ Ponderosa pine, sugar pine, and western 
white pine. California, Oregon, and 
Washington. 
PSCC OTNIGhsS Hopke = 2l a. Saas Ponderosa pine. California. 
aU CU DIRE O [) Keke tents SEE Ey Ponderosa pine, Mexican white pine, and - 
lodgepole pine. Southern Rocky Moun- 
tains. 
PTC LUCHELOD Kee 2 ta es See Monterey pine, Bishop pine, knobcone pine, 
and lodgepole pine. California and Wash- 
ington. 
Pamurravancie Hopk=—-—--—-— = - = = Lodgepole pine. Eastern Oregon, Washing- 
ton, and the northern Rocky Mountain 
region. 
PP eCUUELCT bel OK sees = a Western white pine. Northern Rocky 
Mountains and northward into Canada. 
eRe GSCLOLAUS AuCG = ee Oe oS Douglas fir. Oregon, Washington, and Brit- 
ish Columbia. 
Pepper weloOpke <2) | 2k es ee Balsam firs. Oregon, Washington, Idaho, 
and British Columbia. 
PREOUPIGCULELO kts et es eta Alpine fir. Rocky Mountains. 
iP costatuseMannh= = Sitka spruce. Oregon to Alaska. 
Pcoloradensis Hopk.—-___--_=__ Spruces. Rocky Mountains. 
IPAMaSCENSISTELOP ket S22 Engelmann spruce and probably’ other 
spruces. Montana and northward into 
Alaska. 
(Also see terminal-feeding Pissodes, p. 338.) 
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 outside 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 owing 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 
marked 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. 
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