INSECT ENEMIES OP WESTERN FORESTS 



203 



Figure 97. — The hemlock bark maggot (Cheilosia alaskensis) : A, Resin mass 

 with exit hole made by adult fly; B, longitudinal section of similar mass, 

 showing wound in inner bark and outer sapwood, pupal chamber and exit 

 hole in outer pitch mass, and original beetle entrance connecting them; 

 C, healing wound in inner bark beneath mass like that shown in A; D, 

 wound; E, longitudinal section of wound; F, maggot; G, puparium; H, 

 pupa; /, adult male; J, head of female: K. head of larva; L, antenna. 

 F, G, H, I, and J X 2; K X 20; L X 4b; (Burke). 



the black check in western hemlock (fig. 97) and is distributed 

 from Oregon to Alaska. C. hoodiana Bigot does similar work in 

 white and grand fir in the same region and has also been reported 

 from New Mexico. There are several other species whose habits 

 are not fully known, which cause similar wounds in other western 

 conifers. 



INSECTS WORKING IN SEASONED OR DECAYING WOOD 



POWDER-POST BEETLES 



A group of beetles belonging to the families Ptinidae, Anobiidae, 

 Bostrichidae, and Lyctidae are called powder-post beetles because 

 the larvae burrow into hard, dry wood and reduce it to fine pow- 

 der (101). There are hundreds of species in this group, many of 

 which confine their attack to deadwood in the forest and are of 



