INSECT ENEMIES OF WESTERN FORESTS 201 



make perfectly circular holes in the wood and pack their boring 

 dust in the tunnels behind them. It takes one or two seasons for 

 them to complete their development. Pupal cells are constructed 

 near the surface of the wood, and when the adults mature, they 

 cut round, clean-cut emergence holes to the surface through which 

 to escape. 



Prompt utilization of unseasoned wood exposed to attack by 

 these insects is the best means of avoiding damage. Logs placed 

 in mill ponds and frequently rolled will not suffer from attacks. 

 Kiln-drying gives complete control, destroying the infesting lar- 

 vae, and there is little danger of these insects attacking dry, 

 finished lumber products. 



The different species of horntails are very difficult to distin- 

 guish, and many of the species have not been named or satisfac- 

 torily separated. In many cases the males and the females of the 

 same species have been given different names, since the sexes are 

 markedly different in appearance. Only a few of the more common 

 ones need be mentioned. 



Urocerus calif ornicus Nort. is the largest of the western species. 

 The females are dangerous-looking wasps with black bodies and 

 legs, yellow antennae, yellow bands on legs, patches of yellow on 

 sides of head, and amber wings. They measure from 114 to 2 inches 

 long, and the ovipositors are slightly shorter than the body. The 

 males are smaller and have yellow bodies. The larvae infest true 

 firs, Douglas-fir, and sometimes pine. Urocerus flavicornis F. is 

 a somewhat smaller species, 1 to iy 4 inches long, and black, marked 

 with yellow or red. It breeds in various coniferous trees, including 

 the firs and pines. 



Sir ex calif ornicus Ashm., a dark, metallic, blue-bodied species 

 with buff -colored wings and black legs, is commonly found infest- 

 ing pines in Pacific Coast States. S. juvencus L. is also metallic 

 blue, but the legs are dark red or marked with yellow. It is found 

 in pines, firs, and spruce throughout the West. The western horn- 

 lail (S. aerolatus Cress.) is another metallic-blue species (fig. 96), 

 with black legs and smoky wings. This species commonly attacks 

 redwood, cypress, and cedars, but occasionally is found in pines 

 and other conifers. S. behrensii Cress, is a smaller species, % inch 

 in length, with head and thorax blue black and the apical segment 

 of the abdomen reddish brown. The larvae infest ponderosa pine, 

 sugar pine, and Douglas-fir, and have been found also in Monterey 

 cypress. 



Xeris spectrum (L.) is a very long, slim species, with an ovi- 

 positor at least as long as the body. The abdomen is wholly black 

 and the legs are yellow. It has been found attacking lodgepole 

 pine, Douglas-fir, and grand fir in the Pacific Coast States and 

 Rocky Mountains. X. morrisoni (Cress.) is similar but has a red- 

 dish abdomen. It attacks Douglas-fir, white fir, lodgepole pine, and 

 other conifers in the same regions. 



BARK MAGGOTS 



Peculiar defects in the lumber of certain coniferous trees, con- 

 sisting of dark-brown or blackish resinous scars, with the wood 



