1883. ] Entomology. 85 
of its operations, and have illustrated it with a few rough sketches 
that are all of the natural size excepting those of the insects them- 
selves, which are magnified about nine diameters. 
The hole which constitutes the entrance to the excavation is, 
without exception, at or very near the surface of the ground, and 
is invariably beneath the layer of dead and decaying leaves that 
everywhere covers the soil in our northern deciduous forests. Each 
burrow consists of a primary, more or less horizontal, circular 
canal, that passes completely around the bush but does not perfo- 
rate into the entrance hole, for it generally takes a slightly spiral 
course so that when back to the starting point it falls either a little 
above or a little below it—commonly the latter (see figs. 1 and 2). 
Fics. 1 and 2.—Mines of Corthylus punctatissimus. 
It follows the periphery so closely that the outer layer of growing 
wood, separating it from the bark, does not average .25 mm. in 
thickness, and yet I have never known it to‘ cut entirely through 
this so as to lie in contact with the bark. 
Fics. 3 and 4.—Mines of Corthylus punctatissimus, 
From this primary circular excavation issue, at right angles, and 
