152 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



daily in plantations of Monterey pine. The adult beetles are about 

 y 5 inch in length, dark brown and shining, with parallel sides and 

 one very prominent spine and two smaller ones on the end of each 

 wing cover. The egg galleries are curved or S-shaped, with three 

 or four larval mines issuing from each egg pocket (fig. 69). The 



Figure 69. — Monterey pine engraver (Ips radiatae) : A, Adult X 4; B, 

 pattern of work on sapwood. 



rapidity of development and the number of generations varies 

 with different seasons and localities. Usually there are one or two 

 summer generations and an overwintering generation. The beetles 

 overwinter beneath the bark of trees killed during the previous 

 summer, mostly as adults, but also as larvae and pupae. Some 

 extensive control operations have been undertaken in California 

 to suppress outbreaks of this beetle that developed from roadway 

 slashings. 



The small bark beetles belonging to the genus Pityogenes are 

 sometimes referred to as wood engravers. They usually are of 

 secondary importance and attack the tops, limbs, and twigs, of 

 weakened, dying, and newly felled trees ; but, like other secondary 

 species, under favorable conditions they may develop in sufficiently 

 large numbers to attack and kill small trees growing in the 

 vicinity of their breeding place. The adults are small, slender, 

 dark-brown beetles about % inch long, with two or three small, 

 spinelike teeth along the margin of a slightly concave elytral 

 declivity. The teeth are much larger in the males, with the first 

 pair often developed into prominently curved spines. The females 

 have a deep impression on the front of the head. They are polyga- 

 mous and excavate more or less circular, nuptial chambers under 

 the bark. 



Pityogenes carinulatus (Lee.) is a stout, reddish-brown species 



