84 College of Forestry 
breed in such material in immense numbers. Larve were 
also numerous in pine limbs which had been suppressed by 
shading and in the upper part of pines weakened by 
shading and killed by the attacks of other insects such as 
Dendroctonus valens and Ips longidens.* 
The eggs were laid in larch that was not yet entirely dead, 
as was indicated by the fact that in some cases the early por- 
tions of the burrows are filled with frass saturated with pitch. 
This frass is arranged and packed by the abdomen to form 
the curved strize mentioned in connection with C. blanchardi 
and evidence to indicate that the pitch was successfully 
manipulated by the larva is furnished by curved bands of 
pitchy frass alternating with other bands devoid of excessive 
resin. Still other cases were observed of burrows which had 
been made by this species several years before the death of 
the limb. These had been partly filled with pitchy frass and 
had thus been, to some extent, preserved from decay. The 
bark, however, had later been removed by some unknown 
cause and the burrows partly overgrown by the attempt at 
repair on the part of the tree. 
The burrows made by the larvee of C. dentipes are broader 
than those of any of the other species of flat-head borers in 
larch — fully twice as broad on an average as are those of 
C. blanchardi. The course varies greatly. In one case 
in larch the burrow is longitudinal and nearly straight 
throughout the greater part of its length of nearly twenty 
inches (495 mm.)— this doubtless being due to the larva 
having met no obstructions in its course. In another case a 
piece of pine top nine inches long and shghtly more than two 
inches in diameter contained fifteen larvee. The burrows in 
this piece are very tortuous (Fig. 27), often crossing and 
recrossing each other, so as to make it impossible to trace any 
particular one in its entirety. 
This insect requires two years for the completion of its 
life history. The larve on reaching full growth burrow 
* For the information relative to C. dentipes in white pine we are 
indebted to the notes of Mr. A. J. MacNab, a former graduate student 
in the department. 
