158 



THE SCOLYTID BEETLES. 



they overcome this obstacle. In the meantime the adults will often 

 be found active, even when literally embedded in the semiliquid mass 

 of resin. The gallery is first extended in one direction above the 

 entrance, but later it may be extended below, or, if there is but little 

 resin, may extend downward from the start. Ten to forty or more 

 eggs are placed in an elongated mass along one or both sides of the 

 gallery, and when the larvae hatch they proceed in a body to feed on 

 the bark and ultimately excavate a cavity, often many square feet in 

 extent (fig. 101), which crosses and obliterates the primary gallery. 

 When these large social brood or larval chambers are excavated in the 



Pig. 100.— The red turpentine beetle: Basal wound in living tree resulting from primary injury by 

 this species. Often mistaken for fire wound. (Author's illustration,) 



bark of a living tree, they are often found filled with liquid resin, yet 

 the larvae will continue their work, apparently undisturbed by it. 

 The larvae, which are stout, cylindrical, yellowish- white, footless 

 grubs, with broad dorsal plates on the last abdominal segments armed 

 with six stout spines, transform to pupae and adults in separate or 

 adjoining cells in the borings in the larval chamber or in separate 

 cells extended from the margin or into the roof of the chamber. When 

 the broods of adults are fully developed and ready to emerge, they 

 usually bore through the intervening bark and congregate in the main 

 chamber, where they mate and await the proper time for them to 



