Those chrysalids which have a light colored outer skin are especially
desirable if we would watch this process. One can see through the
semi-transparent membrane the developing butterfly within, until
finally, just before it is ready to break out, the markings of the
wings and body show distinctly. If at this time the chrysalis is
placed in the sunshine it is likely to come out at once, so that you
can observe it readily. It usually breaks apart over the head and the
newly released legs quickly grasp hold of the empty skin as well as of
the support to which it is attached. It then hangs downward with a
very large abdomen and with the wings more or less crumpled up, but
decidedly larger than when they were confined within the chrysalis.
The wings, however, soon begin to lengthen as they are stretched out,
probably through the filling of the space by the body juices.
Commonly, the hind pair of wings become full size before the front
ones. In a short time the wings attain their full size, the abdomen
becomes smaller, through the discharge of a liquid called meconium,
and the butterfly is likely to walk a few steps to a better position
where it will rest quietly for an hour or two while body and wing
tissues harden. After this it is likely to fly away to lead the free
life of a butterfly. (_See plate, page 16._)
These changes from larva to chrysalis and from chrysalis to adult in
the case of the Monarch Butterfly are illustrated on the plates
opposite pages 32-33. A little study of these photographs from life
will help greatly to an understanding of the process.
Some very interesting observations have been made by Mr. J. Alston
Moffat upon the method of the expansion of the wings. In summarizing
his investigations he writes:
"When a wing is fully expanded, and for an hour or two after, the
membranes can be easily separated. Entrance for a pin-point between
them is to be found at the base of the wing where the subcostal and
median nervures come close together. The membranes are united at the
costal and inner edges, which have to be cut to get them apart; but
they are free at the outer angle. At that time the nervures are in two
parts, half in one membrane and half in the other, and open in the
centre. The fluid which has been stored up in the pupa enters the
winglet at the opening referred to, expanding the membranes as it
passes along between them, and the nervures at the same time, and when
it has extended to every portion of the wing, then it is fully
expanded. The expanding fluid is of a gummy consistency, and as it
dries, cements the membranes together, also the edges of the
half-nervures, and produces the hollow tubes with which we are so
familiar."
BUTTERFLIES AND MOTHS
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