14 



and also in the bark on the roots of the stump of a recently felled 

 tree in the Black Hills. This is also a common species of the Rocky 

 Mountain pine regions. 



Branch and twig teethes. — The large and small branches and termi- 

 nal twigs of the trees that were dying from the attack of the pine- 

 destroying beetle were found to be infested by a number of described 

 and undescribed species of the genus Pityophthorus and by Pityogenes 

 cariniceps, all of which attack the bark as soon as the trees commence 

 to die, and contribute, more or less, to hastening the death of the trees. 



Ambrosia or timber beetles and wood-boring grubs. — The wood of the 

 trees was found to be infested by the Western hemlock wood stainer 

 (Gnathotrichus sidcatus Lee), the Western pine wood stainer (Gnatho- 

 trichus occidentalis Hopk. MS.), and several unidentified Buprestid 

 and Cerambycid larvae, which attack the trees, and when they com- 

 mence to die bore into the sapwood and contribute to its rapid decay 

 by giving entrance through their burrows to wood-decaying fungi. 



SMALL TREES DYING FROM OTHER CAUSES. 



The rock-pine pitch ivorm. — In addition to the trees killed by the 

 pine-destroying beetle, quite a number of young pines 2 and 3 inches 

 in diameter were found in the vicinity of Spearfish and Crow Peak 

 that were seriously injured by the larva of an undetermined Sesiid 

 moth working in the living bark of the main stem and causing ugly 

 wounds. Successive attacks on the same tree weaken its vitality and 

 attract the Oregon Tomicus and species of Pityogenes and Pityophtho- 

 rus, which infest the main stem and branches, while a number of the 

 root-infesting bark beetles and a pine weevil attack the base and roots, 

 and the tree soon dies. Only a dead and dry larva and a dead chrysa- 

 lis of this insect were found. The characters exhibited by these speci- 

 mens do not agree with the descriptions of the larva of the sequoia 

 and pine-destroying Sesiid (Bembecia sequoia= Vespamima sequoice Hy. 

 Edw. a ) or of the larva and chrysalis of the pine Sesiid {ITarmonia 

 pini= Parharmonia pini Kellicott b ) . 



The destructive habits of this class of enemies of trees (which 

 includes the common peach-tree borer) suggest that this may be a 

 common and destructive enemy of "reproduction" pines in the Black 

 Hills and other pine-producing areas of the West. 



The pine weevil. — In another section near the Wyoming and South 

 Dakota lines many young trees were observed which were apparently 

 dying from the attack of a pine weevil (Pissodes sp.), or the combined 

 attacks of this insect, a root fungus disease, and a number of species 

 of bark beetles. 



a Mem. Am. Mus. Nat. Hist., vol. 1, part vi, Mongr. Sesiidse. Am. North of Mex. 

 1901, p. 263, with bib. ref. 

 b Ibid., p. 264. 



