The thorax is smooth, the wing cases large, folded under the body
like a scarf and coming almost to the middle of the abdomen. This
has nine segments, of which four, starting with the second, are
armed, on the back, down the middle, with a belt of little horny
arches, pale brown in color, drawn up parallel to one another, set
in the skin by their convex surfaces and finishing at both ends
with a hard, black point. Altogether, the belt thus forms a
double row of little thorns, with a hollow in between. I count
about twenty-five twin-toothed arches to one segment, which gives
a total of two hundred spikes for the four rings thus armed.

The use of this rasp, or grater, is obvious: it gives the nymph a
purchase on the wall of its gallery as the work proceeds. Thus
anchored on a host of points, the stern pioneer is able to hit the
obstacle harder with its diadem of awls. Moreover, to make it
more difficult for the instrument to recoil, long, stiff bristles,
pointing backwards, are scattered here and there among the
climbing belts. There are some besides on the other segments,
both on the ventral and the dorsal surface. On the flanks, they
are thicker and arranged as it were in clusters.

The sixth segment carries a similar belt, but a much less powerful
one, consisting of a single row of unassuming thorns. The belt is
weaker still on the seventh segment; lastly, on the eighth, it is
reduced to a mere rough brown shading. Commencing with the sixth,
the rings decrease in width and the abdomen ends in a cone, the
extremity of which, formed of the ninth segment, constitutes a
weapon of a new kind. It is a sheaf of eight brown spikes. The
last two exceed the others in length and stand out from the group