Insects Bred from American Larch 85 
somewhat, dependent both upon the ultimate size of the indi- 
vidual making the burrow and upon the width of the burrow 
itself. In C. sex-signata the gallery leading to the pupal 
chamber is also noticeably wider — 7. e., is a flatter oval in 
cross section — than in the other species. The general char- 
acter of the burrow of this species is well shown in Fig. 26, 
although it should perhaps be stated that it is rarely that the 
entire course of the larval mine is so readily to be seen as it is 
there. This species requires two years for its life history, 
the adults emerging in midsummer. Our record includes 
specimens emerging nearly daily from June 21 to July 30. 
The associated insects are the same as for Neoclytus lon- 
gupes. 
Chrysobothris dentipes Germ. 
Chrysobothris dentipes seems to occur throughout the 
greater part of southern Canada and the timbered areas of 
the United States. The earliest record of a host plant for 
this flat-head is that of Harris (1862, p. 42), who says that it 
“inhabits the trunks of oaks”. This is confirmed by Fitch 
(1859, p. 793) and by Packard (1890, p. 60). Blanchard 
(1889, p. 31) and Crittenden (1889, p. 219) record it as 
common on pine and the latter concludes that “ it is doubtful 
if it breeds in any but coniferous trees”. This latter view 
seems to us not at all well taken, on account of the definite 
records from oak and in view of the well known fact that 
several species of this genus attack a large number of both 
coniferous and broad-leaved trees and even shrubs with little 
apparent preference. Packard (1890, p. 680) has taken 
dead adults of this species from beneath the bark of pine 
and Felt (1906, p. 657) records it from hard pine. It has 
been bred in our laboratory not only from larch but also from 
white pine. 
In depositing their eggs the adults of C. dentipes choose 
much the same sort of material as do the other species al- 
ready treated. They prefer the thin barked portions of larch 
and pine which is either weakened, dying or recently killed. 
Pine “slash” affords excellent conditions and they will 
