INSECT ENEMIES OF WESTERN FORESTS 115 
The smaller western pine engraver (/ps latidens Lec.) usually 
confines its attacks to the tops and limbs of dying or weakened 
pines and seldom causes any primary injury. Under favorable con- 
ditions, however, it has demonstrated its ability to kill trees, par- 
ticularly those weakened by mistletoe or drought, and in some 
instances even healthy trees of small diameter. It is quite common 
in the tops of lodgepole pines killed by Dendroctonus beetles, and 
during severe epidemics of the mountain pine beetle it often de- 
velops in such numbers as to attack and destroy many small trees 
throughout the area. The adults are the smallest of the western 
species and are about one-eighth inch in length. They are distin- 
guished by having three small, spinelike teeth along the margin of 
the elytral declivity, which is nearly vertical. Its typical work 
consists of from two to five rather short, sometimes curved, egg 
galleries radiating from the central nuptial chamber. It is distrib- 
uted throughout most of the Western States, where it attacks pon- 
derosa, sugar, digger, lodgepole, western white, and probably other 
species of pine. J/. guiéldi Blkm. is a closely related form which 
attacks lodgepole and probably other pines in Colorado and the 
central Rocky Mountain region. 
The sawtooth pine engraver (/ps integer Eichh.) 1s distributed 
throughout the Western States, but is found most commonly in the 
Rocky Mountain region. It generally breeds in weakened or felled 
ponderosa pine, lodgepole pine, western white pine, and western 
larch, but under favorable conditions 1t may become primary. The 
stout, brownish-black adults are about one-fifth of an inch in length 
and have four spinelike teeth along the margin on each side of the 
concave elytral declivity. This species constructs three or four straight 
longitudinal egg galleries that fork from the common entrance or 
nuptial chamber. The egg niches are so thickly and evenly spaced 
along the sides of the egg galleries as to give these a sawtoothed 
appearance—a distinctive feature of this species’ work. 
The California pine engraver (/ps plastographus Lec.) is a species, 
closely related to J. ¢nteger, which prefers to attack the trunks and 
branches of felled Monterey, Bishop, and lodgepole pine, but at 
times also attacks weakened or dying standing trees. It is not often 
primary in its attacks, but is usually associated with the Monterey 
pine engraver and the red turpentine beetle in the killing of living 
trees or trees injured by fire or other causes. It is found through 
the range of its host trees in the coastal belt of middle California 
and in the Sierras. The adults are about one-fifth of an inch in 
length, with four pairs of spines on the posterior margin of the 
wing covers. The work pattern is very similar to that of 7. confusus, 
the typical form having three egg galleries from 5 to 15 inches in 
length, issuing from each entrance chamber. There are from three 
to five generations annually, depending on the locality and season. 
The Oregon pine engraver (/ps oregont Eichh.) is probably the 
most common /ps beetle found throughout the Western States, where 
it attacks ponderosa pine, lodgepole pine, sugar pine, Jeffrey pine, 
digger pine, and probably other species (fig. 56). Large numbers 
develop in such host material as windfalls, freshly cut logs, pieces 
of slash over 2 inches in diameter, and in the tops and limbs of 
trees killed by Dendroctonus beetles. When conditions are favor- 
able and suitable host material is plentiful, they frequently develop 
