148 
POPULAR SCIENCE REVIEW. 
grub, about half an inch long, having the head and the anterior 
segments narrow, the first three segments of the body furnished 
with jointed legs, and the extremity of the abdomen with a 
short process (anal proleg), which serves the animal as an addi- 
tional limb in adhering to the plants on which it feeds. The 
head, the hinder margin of the first body-segment (prothorax), 
and the legs are black, and two rows of black spots are to be 
seen along each side of the body. 
In many, if not in most of the insects belonging to the 
family Chrysomelida3, the anal proleg of the larva serves 
another purpose besides that of assisting its progression ; it pro- 
duces a viscid secretion, by which the larva fixes its tail to the 
surface of a leaf or other object before passing into the quies- 
cent pupa state. There has been some discussion among 
American entomologists as to whether the Western potato- 
beetle ever employs its proleg in this manner, and the question 
does not seem to be quite satisfactorily settled ; but Messrs. 
Eiley and Shimer — the former of whom claims to be the first 
who ascertained the history of the insect through all its changes 
— maintain that it never undergoes its pupal transformation 
attached to the plant on which it has been feeding, but always 
descends to the earth, and under its protection sleeps out the 
pupa stage. In this state (fig. 2) the insect is a small oval 
body, roughly showing at its surface the forms of the various 
organs of the perfect beetle (head, legs, elytra, &c.), folded to- 
gether and confined by a skin, which will be thrown off when it 
emerges as a beetle. The insects of the first and second broods 
of each year remain in this condition ten or twelve days, when 
they issue forth as perfect beetles, and the females quickly pro- 
ceed to lay their eggs upon the potato-plants. How long the 
pupse of the third or last brood continue without further de- 
velopment does not appear to be very clearly known ; but all 
recent observers agree that the perfect insects are produced 
before or during the winter, and that they remain underground 
until the spring. It seems to be certain that the beetles are 
found fully developed in the ground during the winter, although 
their descending to a depth of eight or ten feet, as stated by 
Mr. Eiley, seems quite incredible, considering the form and 
structure of the insect. The same writer, however, says that 
they seldom go down below eighteen or twenty inches ; probably 
they generally remain within the portion of ground which has 
been broken up in digging the potatoes, as this would furnish 
them with ample protection against the direct influence of cold, 
and the beetles would have no difficulty in making their way 
between the clods to a suitable shelter. 
A curious quality has been ascribed to the Colorado potato- 
beetle, and, according to Mr. Eiley, upon authentic evidence in 
