STATE AGRICULTURAL SOCIETY. 
443 
POTATO-BEETLE. LARVjE COVERED WITH FILTII. 
each side, and next to these stripes a dusky cloudiness is perceptible, form¬ 
ing a broad stripe upon each side, at least on the anterior part of the body. 
The head is about as broad as the first ring of tho body, from which it is 
separated by a deep and widely constricted neck. It is flattened-spheiical, 
smooth and polished, and of a coal black color. The first ring is black 
above, cut across in the middle by a pale longitudinal line. The three 
pairs of legs are glossy black, arid are placed anteriorly, on the three first 
rings. Back of these, on the underside of each of the other rings of the 
body are two retractile tubercles serving as pro-legs. When fully grown 
the larva is over three-tenths of an inch in length, and is twice or thrice as 
long as wide, its dimensions varying very considerably as it is elongated 
and in motion or contracted and at rest. 
These larvae are commonly wetted over with a glutinous fluid which is 
copiously secreted from their skin. The most singular trait in their econ¬ 
omy, however, is their habit of covering themselves with their excrement. 
The orifice from which this excretion is voided, instead of being placed at 
the tip of the last ring of the body as iaall other insects, opens upon the 
upper side of this ring, forward of the tip, and in a direction to project the 
feculent matter forward upon the surface of the back. And the glutinous 
fluid with which the skin is wetted holds this feculent matter to the back, 
and at the same time prevents its drying and adhering to the skin. Thus 
it is by degrees pushed forward and molded to the convex surface of the 
back untif it nearly covers it, like the shell with which the tortoise is 
covered. The larva is able to cast off this covering, at will, and renew it 
again in a few hours’time; and these castoff masses of excrement may 
frequently be noticed upon the potato leaves. The clusters of these worms 
being so wet and slimy and coated over as they arc with this excrement 
present a most filthy and disgusting appearance. 
Several of the foreign species of this genus, when in their larva state, 
have this same habit of covering their backs with a layer of slimy excre¬ 
ment. For what purpose do they coat themselves in this nasty manner ? 
Writers generally have supposed it was to protect their soft tender bodies 
from the heat of the sun. This idea is naturally suggested horn seeing 
these larva} as we so frequently do, upon clear summer days when the 
warmth is quite oppressive, the wet with which they are coveiod gi\ing 
them an aspect of such refreshing coolness. But there is reason to distrust 
the correctness of this opinion. These larvse on the potato vines aie always 
stationed on the underside of the leaves where they are shaded from tho 
direct rays of tho sun, and are elevated but a foot or two from the eaith, 
the humidity arising from which keeps the atmosphere constantly cool down 
among the mass of foliage where they reside. On cool cloudy days they 
cover themselves with this excrement the same as on hot sunshiny dajs. 
Upon a cloudy day in July, when a north wind had reduced tho temper atuie 
below sixty degrees, I removed its coat lrom one ol these larvae, atrd 
although there was no sunshine and no warmth or dryness to the atmosphere 
to induce it to renew its coat, it nevertheless did renew it, as I found on 
returning to it some time afterwards. Moreover, upon some of the hottest 
days of summer, when they should most need this protection, one and 
