INSECTS AFFECTING FOREST TREES. 



487 



PINE BARK BEETLE. 



Toiiiicus pint Sa)-. 



This is a small form like the preceding, and measures only about V^, of an inch 

 in length. It is confined almost entirely to the thinner bark near the middle por- 

 tion of the trunk and to that of the larger limbs. This species is associated with 

 larger forms, specially roiiiicus calligraplius Germ., and appears to confine its attacks 

 largely to the white pine, though it has been recorded in spruce and larch. This 

 borer was breeding in large numbers August 18, 1901, at Saranac Inn, in a small 

 dying white pine about 1 8 inches in diameter. The tree was abundantly infested 

 about midway of its height, and a few beetles were found at the top and near the 

 base. This species was also met with by the writer in considerable numbers under 

 the bark of the larger limbs of a large dying white pine at Lansingburgh, which was 

 abundantly infested with Toiiiicus calligraplius Germ. The same conditions were 

 found to obtain at Bath-on-the-lludson, e.Kcept that the attack was more advanced. 

 The destructive work of this species was also observed by the writer at Round 

 Lake, N. V., and it was brought to his attention by a correspondent residing at 

 Catskill, where 50 pines 25 to 30 years old had died during the summer of 1901, and 

 in this latter instance it is very probable that this species was the primar\- cause of 

 the injury. 



Description. The beetle is slightly larger than Tomicus cacograpJius Lee, being 

 about '-• ji of an inch long and usually a little stouter. It varies in color, like the 

 preceding, from light to very dark brown. One of the 

 most prominent characteristics of this beetle is the 

 presence of but four teeth on each side of the conspicu- 

 ous elytral declivit)' or excavation. They are arranged as 

 follows : The dorsal one near the median line is minute 

 and sometimes wanting in the female; the second and 

 third are larger, specially the latter, and touch at the base; 

 the fourth is much smaller and independent, figure 7. 

 The prothorax is rather coarsely granulated and the 

 el_\'tra or wing covers are ornamented with longitudinal rows of rather small 

 punctures. 



The typical form of the burrows of this insect is well shown in plate <S, figure 3, 

 which i-cpresents the central or entrance chamber and a long adult gallery, which is 

 about ' ,„ of an inch in dian'.eter, from whicli may be seen the somewhat tortuous 

 expanding lar\al mines, which are rarely more than J.j an inch in length. The speci- 



v.- -''^ 



\ 



FIG. 7. DECLIVITY OF TOMI- 

 CUS PIN I. 



ORIGINAL. 



