22c 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



c) Shrub stratum. — Here we have the young pines, the juniper, and 

 the willows. From the evergreens we secured several spiders (Philo- 

 dromits alaskensis, Dendryphantes octavus, Theridium spirale, and 

 Xysticus formosus) (172), and with them sometimes an assassin-bug 

 (Diplodius luridus). On the willows are some characteristic willow- 

 feeders, but they appear to prefer the more mesophytic depression 

 shrubs. 



Inhabitants of the Pine 



Fig. 195. — The nest of the kingbird (Tyrannies tyrannus Linn) in a pine tree. 

 The nest is made from the string of a fisherman's net. 



Fig. 196. — The pitch mass of the pitch-moth (Evetria comstockiana ?) ; twice 

 natural size. 



Fig. 197. — The larva removed from the mass. 



Fig. 198. — The larva of the pine engraver beetle (Ips grandicollis); much 

 enlarged. 



Fig. 199. — The adult of the same, from Pinus banksiana. 



d) Tree stratum. — The pine is attacked by many borers and few 

 leaf-feeders. Of the borers several broad-headed grubs have been taken. 

 The bark beetle (Ips [Tomicus] grandicollis) (Figs. 198, 199) (137) is 

 common under the bark of dead and dying trees, especially on the north 

 side, where the trees stand unprotected. The twigs are attacked by the 



