(_Danais Archippus._)
[Illustration: Fig. 13.]
If our readers will look at fig. 13, _a_, they will see how the
caterpillar appears after it has suspended itself. Yet it is not
motionless, but keeps continually stretching forth its head and bringing
it in again, with very much the same motion as is made while feeding,
with the edge of the leaf between its claws, beginning as far from
itself as it can reach, and cutting it down as it draws the head in
towards the body. What this movement of the head has to do with the
changes that are going on within its body we can not say, but for some
reason it keeps up this motion with very little intermission until it is
ready to cast off its skin. The approach of this event may be known by
its shrivelled appearance, the fleshy horns have become withered and
almost dry looking, and the skin is wrinkled and thin. The caterpillar
occasionally draws itself up and strains itself, until it succeeds in
bursting the skin on the back not far from the head. And now commences a
series of movements very difficult accurately to describe, but wonderful
to look upon. The creature stretches and contracts its body with an
astonishing rapidity, and at each movement forces the skin upwards,
until it has reached the spot from which it is suspended. At the hinder,
or what is now the upper, end of the body, there has been formed beneath
the skin a black little spike, crowned at the extremity with a number of
little hooks by which it is to fasten itself to the silken knob from
which it is hanging. To withdraw this black spike from the shrivelled
skin that envelopes it, and fasten its hooks into the little knob, so
that it can hang there while the skin falls to the ground, is the feat
now to be performed.
Fig. 13, _b_, represents the creature at this most interesting and
critical moment. How shall it sustain itself in mid-air while this is
being done? It has neither hands, nor feet, nor mouth by which to hold
on and keep itself from falling. And yet it will do this very thing, and
though the writer has witnessed this performance probably not less than
a thousand times, he has never seen it fail to succeed. Who taught this
creature how?
Look now at fig. 13, _c_, and you will learn how it is done. It seizes a
portion of the skin between the joints of the upper portion of the body,
and compressing the joints together, holds securely by the skin while it
withdraws the black spike, and bending it over the mass of skin fastens
the hooks with which the point is armed into the silken knob, and then,
letting go of the skin, it wriggles itself about, bedding the hooks more
securely in the silk, and working the skin loose from its fastening
until it drops to the ground.
[Illustration: Fig. 14.]
When this has been accomplished, it ceases its hurried movements, as
though wearied by its own exertions, and slowly contracts the upper
segments until it assumes the appearance shown in fig. 14. In a little
while it will have become quite hard and motionless. If you touch it,
there will be no evidence that it feels your touch, and to you it will
feel cold and lifeless. But it is a pretty object to look upon, of a
beautiful pale-green, dotted with gold, with a crimped band of gold
margined with black more than half way around the body; it seems to be a
casket containing something of more than common interest.
In about a week the chrysalis will begin to change its color, gradually
growing darker until the green is entirely gone, and the colors of the
butterfly within can be distinctly seen through its now transparent
walls. The butterfly is now ready to come out of its prison, and while
you are watching it a sudden crackling noise announces the fact that the
chrysalis has been split, and the head and fore legs of the butterfly
begin to appear, followed very speedily by the whole body. And it looks
almost as if it were all body, for the wings are very small indeed, and
seem to be but mere rudiments of wings, wholly unsuited to the purpose
of supporting such a body in the air. The butterfly now seeks a place
where the wings can hang freely, often remaining hanging to the empty
chrysalis, or under surface of some support, to which it fastens by
means of its claws. In this position the wings grow with a rapidity that
is most marvellous. They are not folded up and merely unfolded, but
actually grow from the size of the wings of a large bee until they
measure four inches across, and that within thirty minutes.
The appearance of the butterfly when its wings are fully grown may be
seen at fig. 15. The ground color of the wings is a bright orange-red,
margined with black, and dotted with white spots in the black border.
[Illustration: Fig. 15.]
We have given this account of the history of this insect, not because it
does any injury to our crops of fruit or grain, but because its history
illustrates the metamorphoses of many other insects, and any who wish
can easily rear it in confinement, and watch the changes it undergoes.
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