INSECT ENEMIES OF WESTERN FORESTS 



211 



Figure 101. — Nest of the Great Basin tent caterpillar {Malacosoma fragilis) 

 on defoliated bitterbrush. 



live in small round holes in the ground, from which they emerge 

 during the night or on dull days to feed on any green vegetation 

 nearby. During mild or wet seasons vast areas of range land 

 may be almost denuded. The spreading of poisoned-bran mash, 

 such as is used for grasshoppers, is an effective control measure. 



NATURAL CONTROL 



The question is frequently asked, "Where did these destructive 

 forest insects come from?" The answer is that most of them 

 have been here as long as the forest trees on which they feed. 

 Nearly all species of western forest insects, both injurious and 

 beneficial, are native to these forests and are distributed through- 

 out the range of their favorite host. Occasionally foreign pests 



