Most of our readers will recognize in the accompanying cut, FIG. 1, an
object with which they are more or less familiar, although they may know
little of its origin or the nature of its contents.
[Illustration: FIG. 1.]
During the Winter months, when our trees and shrubs are leafless these
curious silky structures are readily seen, and are found on many
different trees and shrubs, but perhaps oftener on the twigs of apple
trees and currant bushes than anywhere else. They are the cocoons of a
very large and beautiful moth, called the Cecropia moth, (_Attacus
Cecropia_,) which thus spends the winter in a quiet and torpid
condition.
If you cut a twig on which one of these cocoons has been hung, and shake
it, you will feel that it contains a heavy body which is to some extent
moveable, and you can feel a slight dull thud as it falls from side to
side. This winter home of the insect is about three inches long, shaped
something like a pod, tapering towards each end, and invariably fastened
lengthwise to the twig. It is of a dirty brown colour; the exterior is
very close and papery like, although much wrinkled, and is quite
impervious to wet. Let us look inside of it; underneath the close
exterior we find a mass of loosely woven threads of strong yellow silk
which surround the dark brown chrysalis and fill the intervening space,
the upper end of the cocoon where the moth is eventually to make its
escape, being much looser in texture than the other portions. The
chrysalis itself, the object of all this care, is smooth, of a dull
brown colour, and about one and a half inches long, and 5/8 of an inch
broad in the widest portion.
Early in June—or if the cocoon is kept in a warm room, many weeks
before this—a marvellously beautiful moth issues from this snug
enclosure. When the time has come for its escape, the shelly structure
of its prison house is rent, split open along the back, and at once
restless movements begin within; the struggling creature as it tries to
free itself, making a scratching noise as it tears away the silken bars
which stand between it and the outer world, and this noise can be
distinctly heard at some distance from the object. At this juncture a
fluid is secreted from the mouth of the insect which so softens the silk
as to make the escape of the moth a comparatively easy matter, while
without this wise provision it might remain in its cell and exhaust
itself in fruitless efforts to get out. Presently the fore legs appear,
thrust out of the upper end of the cocoon, then the head crowned with
its beautiful feather-like antennæ; and very soon a heavy looking object
with a large plump body and soft clumsy little wings is drawn slowly out
of the orifice, and stands before you in the free air.
The first care of the moth is to place itself in such a position that
its wings may hang downwards, the only favourable posture for their
proper development, then a rapid process of growth or expansion begins,
resulting in full maturity in about half an hour, during which time the
wings enlarge from the size of an ordinary bumble bee until they measure
from five to six inches across.
This magnificent creature is nicely represented in Fig. 2. Both front
and hind wings are of a rich brown; the anterior pair greyish, shaded
with red, while the posterior are more uniformly brown; about the middle
of each of the wings there is a nearly kidney-shaped white spot, shaded
more or less with red, and margined with black. A wavy dull red band
crosses each of the wings, bordered within on the front wings, more or
less faintly with white, while on the hind pair the band is widely and
clearly margined with the same colour. The outer edges of the wings are
of a pale silky brown, in which, on the anterior pair, runs an irregular
black line which on the hind wings is replaced by a narrow, double
broken band of the same hue. The front wings next to the shoulders are
dull red with a curved white and black band, varying in distinctness in
different specimens, and near their tips there is an eye-like black spot
with a bluish-white crescent. The upper side of the body and the legs
are dull red, with a wide band behind the head, and the hinder edges of
the rings of the abdomen white; the under side of the body is also
irregularly marked with white. Below, the wings are very much like the
upper surface, but paler.
[Illustration: FIG. 2.]
These gay creatures are nocturnal in their habits, flying like bats in
the dim twilight and dusky night. After pairing, the female deposits her
eggs, numbering 200 or more, a process which occupies some time, as the
eggs are not laid in patches, but fastened singly with a glutinous
material, usually on the under side of a leaf. The eggs are about
one-tenth of an inch long, nearly round, of a dull creamy white colour,
with a reddish spot near the centre. They usually hatch in about a week
or ten days.
The subsequent history of this curious and beautiful insect will be
given hereafter.
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