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Footnotes
1
Plural
Chrysalides
.
CHAPTER II. The Imago.
CHAPTER II.
"COMING OUT"—ICHNEUMONS—THE BUTTERFLY PERFECTED—ITS WINGS—LEPIDOPTERA—MEANING OF THE WORD—MICROSCOPIC VIEW—NEW BEAUTIES—MAGNIFIED "DUST"—THE HEAD AND ITS ORGANS—THE TONGUE—THE EYES—THE ANTENNÆ—THEIR USES—INSECT CLAIRVOYANCE—AN UNKNOWN SENSE—FORMS OF ANTENNÆ—THE LEGS.
We now arrive at the last stage, the consummation of all this strange series of transformations; for veritable transformations they are to all intents and purposes; though some learned naturalists have discovered—or imagined so—that the butterfly, in all its parts, really lies hid under the caterpillar's skin, and can be distinguished under microscopical dissection; and that, therefore, the so-called transformations are merely the throwing off of the various envelopes or husks, as they become in turn superfluous, as a mountebank strips off garment after garment, till lastly the sparkling harlequin is discovered to view; or, in more exact language, they consider these changes in the light rather of successive developments and emancipations of the various organs than as their actual transformations. Still, it seems to me, the difference is chiefly one of terms. The real wondrous fact remains undiminished and unexplained; that a creeping wormlike creature, in process of time, is changed into a glorious winged being, differing from the former in form, habits, food, and every essential particular, as widely as any two creatures can well differ, as widely as a serpent from a bird, for instance.
As the imprisoned butterfly approaches maturity, a change is observable in the exterior of the chrysalis, the skin becomes dry and brittle, usually darkens in colour, and if the enclosed butterfly be a strongly marked one, the pattern of its wings shows through, often quite distinctly.
When the fulness of time arrives, the creature breaks through its thin casings, which divide in several places, and the freed insect crawls up into some convenient spot to dry itself, and allow the wings to expand.
All the organs are at first moist and tender, but on exposure to the air soon acquire strength and firmness.
At the moment of emergence, the wings are very miniature affairs, sometimes hardly one-twentieth of their full size when expanded; but so rapid is their increase in volume, that they may actually be seen to grow, as the fluids from the body are pumped into the nervures that support the wing-membrane, and keep it extended.
In the more strongly marked, or richly coloured species, it is a wonderfully beautiful sight to watch this expansion of the wings, and to see the various features of their painted devices growing under the eye and developing gradually into their true proportions.
Generally within an hour the development is complete, and the wings, having gained their full expanse and consistency by drying in the sun, are ready for flight, and the glad creature wings his way to the fields of air, and enters on that life of sunshine and hilarity which is associated with the very name of "Butterfly."
But not every chrysalis arrives at this happy consummation of its existence. Supposing that you have reared and watched a caterpillar to apparently healthy maturity, that it has duly become a chrysalis, and you are awaiting its appearance in butterfly splendour—peeping into your box some morning to see if the bright expected one is "out," be not surprised if in its stead you find the box tenanted by a swarm of little black flies—an impish-looking crew. Whence came all these? Why they and the empty chrysalis shell are all that remains of your cherished prize; so look no more for the fair sunny butterfly, devoured ere born by that ill-favoured troop of darklings who have just now issued from the lifeless shell.
The truth is, that long since, perhaps in early larva-hood, the creature's fate was sealed; a deadly enemy to his race is ever on the alert, winging about in the shape of a small black fly, in search of an exposed and defenceless caterpillar. Having selected her victim, she pierces his body with a sharp cutting instrument she is armed with, and in the wound deposits an egg; the caterpillar winces a little at this treatment, but seems to attach little importance to it. Meanwhile his enemy repeats her thrusts till some thirty or forty eggs, germs of the destroyers, are safely lodged in his body, and his doom is certain beyond hope. The eggs quickly hatch into grubs, who begin to gnaw away at the unhappy creature's flesh, thus reducing him gradually, but by a profound instinct keeping clear of all the vital organs, as if knowing full well that the creature must keep on feeding and digesting too, or their own supply would speedily fail; as usurers, while draining a client, keep up his credit with the world as long as they can.
Weaker grows the caterpillar as the gnawing worms within grow stronger and nearer maturity. Sometimes he dies a caterpillar, sometimes he has strength left to take the chrysalis shape, but out of this he never comes a butterfly—the consuming grubs now finish vitals and all, turn to pupæ in his empty skin, and come out soon, black flies like their parent.
But, supposing that it has escaped this great danger, we now see the creature in its completest form, as the
IMAGO, OR PERFECT BUTTERFLY.
The first term, Imago, is a Latin one, merely signifying an image, or distinct unveiled form; as distinguished from the previous larva, or masked state, and the pupa, or swathed and enveloped state. The word imago then, in works on entomology, always means the perfect and last stage of insect life, and is applied to all insects with wings—for it must be borne in mind that no insect is ever winged till it reaches the last stage of its existence.
If the progressive development of these lovely beings is so marvellous, no less so is their structure when perfected, and of this some general description must now be attempted.
In contemplating a butterfly, one feels that the mind is first engaged by that ample spread, and exquisite painting of the wings that form the creature's glory; let therefore these remarkable organs have our first attention.
Wherein do these wings chiefly differ from all other insect wings? Certainly in being covered thickly with a variously coloured powdery material, easily removed by handling. This apparent dust is composed, in reality, of a vast number of regularly and beautifully formed scales—feathers they are sometimes called, but they are more comparable to fish scales than to any other kind of natural covering. The general term Lepidoptera, applied to all butterflies and moths, is derived from these scaly-wings; Lepis[2] being the Greek for a scale, and ptera meaning wings in the same language.
The use of a tolerably powerful pocket lens will afford some insight into the exquisite mode of painting
employed in these matchless pieces of decoration; but the possessor of a regular microscope may, by applying it to some of our commonest butterflies, open for himself a world of beauty, and feast his eyes on a combination of refined sculpture with splendour of colouring; now melting in softest harmony, then relieved by boldest contrast—a spectacle, the first sight of which seldom fails to call forth expressions of wonderment and warm delight; and, truly, little to be envied is the mind untouched by such utter beauty as here displayed.
As an example of the method by which this admirable effect is produced, let us take a small portion of the wing of the Peacock, a very beautiful, though an abundant species, and one admirably adapted for microscopic examination, and to illustrate the subject, from the great variety of rich tints brought