Insects Bred from American Larch 79 
Pogonocherus mixtus Hold. 
Pogonocherus mixtus has been reported from Canada and 
from nearly every region of the United States except the 
Southeastern States. Leng and Hamilton (1896, p. 135) 
give the distribution as “ Canada, Maine, New Hampshire, 
Massachusetts, New York, New Jersey, Pennsylvania, Mich- 
igan, Wisconsin, Missouri, Kansas, Colorado, Montana, 
Idaho, California, Arizona.” This species has been taken 
from beneath the bark of willow (Caulfield, 1881, p. 60) 
and “beneath the bark and on the dead limbs of pine 
(Blatchley, 1910, p. 1081). We have bred it both from the 
“shaded out” limbs of white pine and from the limbs of 
larch. 
The eggs are deposited in recently dead thin-barked larch 
or pine. Cracks or other injuries in the bark were utilized 
by the female in ovipositing. In one case in pine the ovi- 
positor had appearently been thrust into the entrance to the 
burrow of Pityophthorus sp. in gaining access to the inner 
bark. The larva on hatching works directly beneath the 
bark, grooving the sapwood deeply. The burrows at first 
are both narrow and shallow, but those made by the full- 
grown larva are from 4 to 7 mm. wide and slightly more 
than 2 mm. deep. The course of the larval gallery is only 
slightly winding, as shown in Fig. 21, and usually the bur- 
row loops back upon its course so that the entrance to the 
pupal chamber often lies not far from the origin of the 
burrow. The burrow is rather short, usually from 110 to 
125 mm. long. The pupal chamber is carried diagonally 
into the wood for a depth of 12 to 15 mm. The larva then 
plugs the opening loosely with medium-fine shreds of wood 
and pupates. Apparently before pupating the larva has 
arranged itself with its head directed back toward its larval 
burrow for the adult on emerging invariably (so far as our 
observations on fifteen cases go) removes the obstructing 
frass and emerges through a nearly circular opening in the 
bark covering the larval mine. The insect requires two years 
for the completion of their growth and the adults begin to 
emerge about the middle of June. 
