INSECT ENEMIES OF WESTERN FORESTS 157 
and there is little danger of these insects attacking dry, finished 
lumber products. 
The different species of horntails are very difficult to distinguish, 
and many of the species have not been named or satisfactorily sep- 
arated. In many cases the males and the females of the same species 
have been given different names, since the sexes are markedly dif- 
ferent in appearance. Only a few of the more common ones need 
be mentioned. 
rs 
$ 
5 
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§ 
bi 
| 
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1 4 44 ad vs 
Figure 78.—Western horntail (Sirex aerolatus): A, Adult male, &* 1.5; B, female, 
xX 1.5; C, larva, X 3; D, pupa, xX 3; EH, exit holes; Ff, larval mines. (EHEdmonston.) 
Urocerus californicus 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 
in length, and the ovipositors are slightly shorter than the body. 
The males are smaller and have yellow bodies. The larvae infest 
balsam firs and Douglas fir and sometimes pine. Uvocerus flavicornis 
F. is a somewhat smaller species, 1 to 114 inches long, and black, 
marked with yellow or red. It breeds in various coniferous trees, 
including the firs and pines. 
Sirex californicus Ashm., a dark, metallic, blue-bodied species 
with buff-colored wings and black legs, is commonly found infesting 
pines. S. juvencus L. is also metallic blue, but the legs are dark 
