INSECT ENEMIES OF WESTERN FORESTS 



61 



Figure 25. — The hemlock chermes (Chermes tsugae) on twigs of western 



hemlock. 



The woolly pine aphid (Pineus pinifoliae (Fitch) ) is found in 

 the Northwest from British Columbia to California and in Idaho, 

 Montana, and Colorado, where it attacks blue, Engelmann, and 

 Sitka spruces, and western white pine. On spruce it forms loose 

 terminal cone-shaped galls somewhat similar to those of Chermes 

 cooleyi, except that the poorly formed chambers are intercom- 

 municating and contain only one or two young in each chamber, 

 and when the insects emerge the galls flare open, and the scales 

 drop from the twigs. 



The alternate form attacks western white pine and is easily 

 recognized by the waxy secretion that appears as a whitish-gray 

 mold on the bark and needles. The attacked foliage is apt to be 

 sparse and stunted ; the needles fall prematurely, and the fascicles 

 or bundle sheaths are left protruding from the limbs as short 

 spurs. The damage is most frequently found on young white pines. 

 In the last few years it has become a rather important enemy of 

 white pine seedlings in eastern Washington, Idaho, and western 

 Montana. The adults appear as little hemispherical, brown scales 



