INSECT ENEMIES OF WESTERN FORESTS 



171 



Figure 78. — The California flatheaded borer (Melanophila calif ornica) : A, 

 Frass-packed channels in inner bark; B, full-grown larvae; C, adults. 

 X 1.6. 



Oregon, Washington, and Idaho. It attacks pines growing on 

 rocky slopes, in fringe-type stands, or in other situations where 

 soil moisture is insufficient for normal tree growth, most fre- 

 quently attacking old, decadent, or unhealthy trees, but thrifty, 

 vigorous trees are not immune. The adults are a greenish bronze 

 and about y 2 inch long. Eggs are laid in bark crevices of selected 

 trees during the summer months. On hatching, the larvae bore 

 into the cambium, where they may feed for a few months or for 

 3 or 4 years without apparent injury to the tree, except a scarring 

 of the sapwood and a general weakening due to blocking of sap- 

 conducting tissues. This is called the incipient stage. If they do 

 not succeed in killing the tree, they finally die in this stage; but 

 if the tree is overcome, the larvae pass into a fast-growing stage, 

 begin to kill the cambium, and rapidly develop. Prepupal larvae 

 appear in the outer bark in July and August, but new adults do 

 not appear until April and May of the following year. This species 

 is of primary importance in weakening trees and causing them to 

 become increasingly susceptible to pine beetle attack. 



The flatheaded fir borer (Melanophila drummondi Kby.) (fig. 

 79) is the species of this group most frequently found throughout 

 the West attacking Douglas-fir, true firs, and hemlock. It also 

 attacks western larch, spruce, and possibly other conifers. Though 

 preferring trees that are dying or recently felled, the beetles some- 



