THE GENUS DENDROCTONUS. 149 



HABITS. 



This species prefers to enter the bark at the base of injured and 

 dying trees and the stumps of those newly felled, though it will 

 attack the main trunk of living trees, and if in sufficient numbers 

 may cause their death without the aid of other agencies. Evidences 

 of this have been noted by the writer on Long Island, N. Y., by 

 Mr. W. F. Fiske in Texas, and by Dr. J. B. Smith (1899) in New 

 Jersey. In the South, however, its principal injury is effected at 

 the base of living pine trees, where its attack causes large scars, 

 usually recognized as basal fire wounds. 



It has been found in practically all of the pines within its range, 

 and a few specimens were taken by Mr. Fiske excavating galleries in 

 spruce in the high mountains of North Carolina. 



A few specimens, taken by the writer in West Virginia from yellow 

 and white pines, appear to represent quite a distinct variety of the 

 normal southern form, while specimens of the normal form were taken 

 from, scrub and pitch pine at Kanawha Station, W. Va. The princi- 

 pal distribution of the species is south of the area occupied by the 

 red turpentine beetle, but the two overlap along the middle Atlantic 

 States from North Carolina to Long Island, New York, and along 

 the mountains from North Carolina to Pennsylvania. 



In its southern distribution it is often found in large numbers in 

 the stumps of felled trees wherever winter and spring timber-cutting 

 operations are carried on, and in lightning or fire-injured trees, but 

 especially in the bark at the base of pine trees killed or injured by 

 other insects. It shows a preference for the base of pine trees and 

 stumps, but will breed in the bark on the underside of prostrate 

 trunks. 



The parent beetles excavate their broad, irregular, sometimes 

 branched, longitudinal egg galleries for a distance of a few inches to 

 many feet, through the inner, living bark. If the bark is living, 

 healthy, and full of resin, the progress in making an entrance through 

 the inner bark and extending the galleries is slow, so that often a 

 large mass of resin, or so-called pitch, is ejected through the entrance 

 burrow before the beetles overcome this obstacle. In the meantime 

 the adults will often be found active, even when literally imbedded in 

 the semiliquid mass of resin. The gallery is first extended upward 

 above the entrance, though later it may be extended downward, or, 

 if there is but little resin, downward from the start. Ten to forty, 

 or more, eggs are placed in an elongated mass at intervals along one or 

 both sides of the gallery. 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, which crosses and obliterates the primary 

 gallery. When these large brood or larval chambers are excavated 



