158 
THE SCOLYTID BEETLES. 
they overcome this obstacle. In the meantime the adults will often 
be found active, even when literally embedded hi 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 
Fig. 100. — The red turpentine beetle: Basal wound in living tree resulting from primary injury by 
this species. Often mistaken for tire 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 larva 1 , which are stout, cylindrical, yellowish- white, footless 
grubs, with broad dorsal plates on the last abdominal segments armed 
with six stout spines, transform to pupa? 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 mam 
chamber, where they mate and await the proper time for them to 
