Plate 1. 
Fie. 1. View of the inner bark of American larch, show- 
ing the burrows of Dendroctonus simplex. The wider 
passages are the egg-galleries made by the adults, while the 
shorter burrows at right angles to them are the larval mines. 
Note the arrangement of the larval mines in alternate groups 
of from three to six on opposite sides of the egg-gallery. This 
is best shown in connection with the egg-gallery at the right- 
hand side of the picture. About four-fifths natural size. 
