266 Transactions.— Zoology. 
* The butterflies hibernate, though whether any but the impregnated 
females survive until the milk-weeds commence to grow, is not definitely 
ascertained. They commence depositing eggs in the latitude of St. Louis 
during the fore part of May. Some of the earliest developed butterflies 
from these eggs begin to appear about the middle of June, and others 
continue to appear for several weeks. These lay eggs again, and the butter- 
flies abound a second time in October. Thus there are two broods each 
year, and though the first brood of larve are hatched more uniformly and 
within a more limited time than the second, the two broods yet connect by 
late individuals of the first and early individuals of the second, and the 
caterpillars may be found at almost any time from May to October, but are 
especially abundant during late summer and early fall. 
**'The egg is invariably deposited on the under side of a leaf, and is conical 
and delicately reticulate with longitudinal ribs, and fine transverse stris. 
It is yellowish when first deposited, but becomes grey as the embryo within 
developes. 
* In about five days after deposition the egg hatches, and the young 
larva as soon as hatched usually turns round and devours its egg-shell; a 
custom very prevalent with young caterpillars. At this stage it differs 
considerably from the mature larva; it is perfectly cylindrical, about 0:12 
inch long and much of a thickness throughout. The head is jet-black and 
polished ; the colour of the body is pale greenish-white, with the anterior 
and posterior horns showing as mere black conical points, and with two 
transverse-oval black warts, nearer together, on the first joint. It is 
covered with minute black bristles, arising from still more minute warts, 
six on the back, and placed four in a row on the anterior portion, and one 
each side on the posterior portion of each joint; and three on each side, one 
in the middle of the joint, and two which are substigmatal, posteriorly. 
There is a sub-triangular black spot on the anal flap, the legs are alternately 
black and white, and the stigmata are made plainly visible by a pale shade 
surrounding them. 
** When the young worm is three or four days old, a dusky band appears 
across the middle of each joint, and by the fifth or sixth day it spins a 
carpet of silk upon the leaf, and prepares for its first moult. After the first 
moult the anterior horns are as long as the thoracic legs, the posterior ones 
. being somewhat shorter; the characteristic black stripes show quite 
distinctly, but the white and yellow stripes more faintly. After this it 
. . undergoes but slight change in appearance, except that the colours become 
brighter and that at each successive moult the horns become relatively 
= longer. There are but three moults, and the intervals between them are 
short, § as the worms kemay acquire their full growth within three weeks 
