Figs. 122, 123.—Cocoon of Pyralis corticalis (magnified, proper size 2/3 inch).Figs. 122, 123.—Cocoon of Pyralis corticalis (magnified, proper size 2/3 inch)."When one sees," he says,[39]"an insect which, to construct a cocoon, begins by collecting together an infinite number of small plates of bark in order to compose of them two flat triangular blades; which, to gain its end, takes means that seem so roundabout, although they are the most suitable and the quickest it could adopt, one is very much tempted to consider such an insect, when one sees it thus acting, possessed of reason."These two blades are at last transformed into a regular cocoon. The little animal, which is at the same time architect, cabinet-maker, and weaver, arranges it in such a way as to form a hollow cone, which it only remains for it to shut. Réaumur calls this sort of cocoon or shell,la coque en bateau, the boat-shaped cocoon. Some caterpillars weave cocoons of the same form with pure silk.To bring this subject to an end, we will mention the industry of the Puss Moth (Dicranura vinula), and that of a smallTinea, which eats the barley stored away in our granaries.The larva of the puss moth employs in the construction of its shell the wood of the tree on which it has lived. It bites it up, and mixing it with a glutinous fluid which it secretes from its mouth, reduces it to a sort of paste, which it then uses in the formation of an envelope, of such hardness that a knife can hardly cut into it.TheTinealines the interior of a grain, of which it has previously devoured the contents, with a coating of silk, and divides it thus into two different chambers. In one of these it is to change into a pupa; in the other it places its excrement. And so the little careful architect constructs its house in such a manner as to find in it tranquillity, cleanliness, and comfort.When caterpillars have not within their reach the materials they are in the habit of employing, like good workmen, they content themselves with what they can get. Réaumur reared a caterpillar which formed its cocoon of pieces of the paper of which the box was made in which it was imprisoned.What an extraordinary condition! what a strange phase of vitality does the chrysalis present to us—a being occupying the middle state between the caterpillar and the perfect insect! How little does it resemble that which it previously was, and what it will become! In appearance it is scarcely a living being; it takes no nourishment, and has no digestive organs; can neither walk nor drag itself along, andhardly bends the joints of its body. The outside skin of the chrysalis appears to be cartilaginous; it is generally smooth, although some species have hairs scattered over their bodies.We distinguish in chrysalides two opposite sides. The one is the insect's back, the other its under side. On the upper part of the latter (Fig. 124) we perceive various raised portions, formed and arranged like the bands round the heads of mummies; the back is plain and rounded in a great number of pupæ; but a great many others have on the upper part, along the edges which separate the two sides, little humps, eminences broader than they are thick, ending in a sharp point (Fig. 125).Fig. 124.A conical pupa.Fig. 125.Pupa having angular projections.Fig. 126.Angular pupa of a Butterfly.The head of the angular pupæ terminates sometimes in two angular parts, which diverge from each other like two horns (Fig. 126). In some other cases they are curved into the form of a crescent. These appendages sometimes give to the pupa the appearance of a mask, especially as an eminence placed on the middle of the back is rather like a nose, and the small cavities may represent the eyes (Fig. 125).The colours of angular pupæ attract our attention. Some are superbly tinted; they appear to be wrapped in silk and gold. Others have only spots of gold and silver on their belly or their back. All, however, have not this remarkable splendour, not these metallic spots. Some are green, yellow, and spotted with gold. Generally they are brown. Réaumur has shown that this golden colour is not due, as was thought for a long while, to colouring matter, but to a little whitish membrane, placed under the skin, which reflects the light through the thin outer pellicle, in such a manner as to produce theoptical illusion which imparts to the robe of the chrysalis the golden hues of a princess in grand costume.All is not gold that glitters, Réaumur proves literally, in the case of chrysalis.[40]Let us add that the chrysalis remains thus superbly dressed as long as it is tenanted, but loses its colour as soon as the butterfly has quitted it.The cone-shaped pupæ belong to the twilight and night-flying Lepidoptera, and to those butterflies whose caterpillars are onisciform, or in shape resembling a wood-louse. They are generally oval, rounded at the head, and more or less conical at the lower end. Their colour is generally of a uniform chestnut brown.What a mystery is that which is accomplished in the transition from the chrysalis to the perfect state! Those great changes from the larva state to that of the pupa, and from the pupa to that of the imago, are accomplished with such rapidity, that the phenomena were looked on as sudden metamorphoses, like those related in mythology. It has been thought also that there was in these changes from one state to another a sort of resurrection. There is here neither sudden metamorphosis, nor, as we will show, resurrection. In fact, the chrysalis is a living being; it indeed shows its vitality by exterior movements. Under the old skin of a caterpillar about to moult, under the envelope which is soon to be cast off, the new integuments are being prepared.Fig. 127.—Chrysalis of the large Tortoise-shell Butterfly (Vanessa polychloros), magnified, seen from the lower side.Fig. 127.Chrysalis of the large Tortoise-shell Butterfly (Vanessa polychloros), magnified, seen from the lower side.Some days before the moult, split the caterpillar's skin, and you will find the skin which is to take its place already beneath. If, some days before the transformation of the caterpillar into a chrysalis, it is dissected, the rudiments of wings and antennæ may be discovered. If a chrysalis is examined on the outside, all the parts of the future insect can be distinguished under the skin: the wings, the legs, the antennæ, the proboscis, &c.; only, these parts are folded and packed away in such a manner that the chrysalis can make no use of them. It could not, moreover, make use of them on account of their incomplete development.Fig. 127shows, after Réaumur,[41]a chrysalis magnified and seen from its lower side, on which we observe:—a, the wings;b b, the antennæ;t, the trunk or proboscis.There is a moment when these parts, pressed one against each other, and as it were swathed up like a mummy, are very easily seen, for they are, as we may say, laid bare. This moment is that inwhich the pupa has just quitted the caterpillar's skin. It is then still soft and tender. Its body is moistened with a liquid, which, drying rapidly, becomes opaque, coloured, and of a membranous consistency. The result is that the parts which did not cohere in the least when the chrysalis made its first appearance, are fastened together, so that although they could at first be seen, through a layer of transparent fluid, they are now hidden under a sort of veil or cloak. It is necessary to seize then the moment of the birth of the chrysalis, to observe it accurately.On examining the pupa before the liquid which pervades these parts has had time to dry, it resembles the perfect insect. All the exterior parts which belong to the imago can be distinguished. One recognises the head, which is then resting on the thorax; the two eyes and the antennæ (Fig. 128), which are brought forward like two ribbons; the wings also brought over the thorax, but these are separated artificially in the drawing we have given after Réaumur;[42]and lastly in the space left between the wings, the six legs, and the body of the insect.Fig. 128.—Chrysalis of the Large Tortoise-shell Butterfly (Vanessa polychloros) whose different parts have been opened before they were fastened down.Fig. 128.—Chrysalis of the Large Tortoise-shell Butterfly (Vanessa polychloros) whose different parts have been opened before they were fastened down.(a, wings;b b, antennæ;t, trunk, or proboscis.)To sum up: the pupa, when it approaches the period for being hatched is only a swaddled butterfly. Directly it has strength enough to rid itself of its wrapping, the insect frees itself from its fetters; it flies away, brilliant and free, and its many-coloured wings glitter in the sun.The duration of the pupa state is variable, according to the species and the temperature. Réaumur placed in a hot-house, in the month of January, some pupæ which, in the ordinary course of things, would not have been hatched till the month of May, and a fortnight afterwards the imagos had appeared. On the other hand, he shut up some pupæ in an ice-house during the whole of a summer, and thus retarded their being hatched by a whole year. The influence of the temperature on the period of emerging, and, consequently, the influence of the seasons on the length of this period, are completely brought to light by these experiments.[43]We will now see how the insect delivers itself from the last skin. To quit the pupa case is not so laborious an operation as it was for the same insect to quit the caterpillar's skin. This is because the pupa case is drier; it does not adhere to every part of the body, and is brittle. Those insects which are enclosed in a cocoon free themselves of the pupa envelope in the cocoon itself. To witness the last operation, the cocoon may be opened, and the pupa drawn out of it with care. If it is then placed in a box, the metamorphosis may be observed. To study this last evolution more at his ease, Réaumur covered a large extent of the wall of his study with pupæ of theVanessa polychlorosand other species.When the parts of the body of the insect have attained a certain degree of solidity within the envelope, it has no great difficulty in making the thin and friable membrane which surrounds it split in different places. If it even distends itself or moves, a small opening will be made in the dried skin. If the movements persist, theopening increases in size, and very soon allows the imago to emerge.Fig. 129.Moth just emerged.Fig. 130.Moth whose wings are folded up.It is on the middle of the upper part of the thorax that the envelope begins to split. The split extends over the middle of the forehead and back. The pieces of the thorax open, separate themselves from the other parts to which they were fixed, and the insect can take advantage of the opening which is made, and escape. Little by little also it advances its head. The head is the first out of the old skin, and the insect sets itself entirely free.This occupies rather a long time; for we must remember that, under the pupal envelope, its legs, its antennæ, its wings, and many other parts, are enclosed in special cases. These peculiar circumstances show that the animal has much trouble and must employ some time in setting free all the parts.At last our prisoner has come out of its narrow cell, and is delivered from its old covering. What poet can describe to us the sensations of this charming and frail creature which has just risen from the tomb, and for the first time is enjoying the splendid light of day, the radiant sky, and the flowers redolent with delicious perfumes, which are inviting it to kiss and caress them!The wings strike one most. They are very small at the time of birth.Fig. 129represents, after Réaumur,[44]a moth at the moment in which it has just emerged from the pupa. But at the end of a short period the wings become developed; only they are wrinkled, asFig. 130, given by Réaumur, represents.Réaumur having taken between his fingers a very short wing of a butterfly which was just hatched, drew it about gently in all directions. He succeeded thus in giving it the whole extent it would have assumed naturally. According to Réaumur the wing of a butterfly just born, which appears so small, is really already provided with all its parts, only it is folded and re-folded on itself. He supposes that what his hands did to lengthen the butterfly's wings, is done naturallyby the liquids which are contained in the insect which has just emerged, and whose wings are no longer confined in their cases. At the time of its birth the wings are flat and thick; as they grow, little by little they spread themselves out and become curled up. When they are completely developed and flattened the wings become firm and hard imperceptibly, and this firmness extends at the same time to the whole of the body.Figs.131and132, borrowed, like the preceding, from the 14th Memoir of Réaumur (sur la transformation des chrysalides en papillons), show the states through which the wings of the same moth pass, before they are thoroughly developed.Fig. 131.—Moth whose wings are developing.Fig. 132.—Moth whose wings are developed.Those pupæ enclosed in cocoons free themselves entirely or in part from their old skin, in the shell itself; but the imago is still a prisoner. It has broken through a first enclosure; it must open itself a way through the second. How does it manage to bore through the often very solid walls of this second prison, so as to regain its liberty? Réaumur states that in the Lackey Moth (Bombyx neustria) the head is the only instrument of which the insect makes use in opening a passage, the compound eyes then acting like files. These files cut the very fine threads of which the cocoon is composed, and as soon as the end of the cocoon is pierced through, the insect uses its thorax like a wedge, to enlarge the hole. It very soon manages to get its two front legs out, fixes itself by them on to the outside, and little by little emerges from its prison.The Perfect Insect.Who does not admire the extraordinary splendour, the vivacity, the prodigious variety of colours of these brilliant inhabitants of the air? Some amateurs have devoted to the purchase of certain butterflies large sums of money. "Diamonds," says Réaumur on the subject, "have perhaps beauties no more real than those of a butterfly's wings; but they have a beauty which is more acknowledged by the world in general, and which is more recognised in commerce." The essential character of butterflies and moths makes them very easily recognisable among all other insects. All have four wings, which are covered with scales, that communicate to them the brilliant colours with which they are decorated. It is these scales which adhere to the fingers when we seize one of these charming creatures.Fig. 133.—Different forms of the scales of Butterflies, after Réaumur.Fig. 133.—Different forms of the scales of Butterflies, after Réaumur.For a long time this dust was thought to be formed of very small feathers, but Réaumur showed that it is composed of little scales. Their form varies singularly, as we may see inFig. 133, borrowed from the Memoirs of Réaumur,[45]which represents the different forms of the scales which cover the wings of Lepidoptera. M. BernardDeschamps has closely studied them. According to this naturalist, they are composed of three membranes, or plates, superposed one on the other, of which the first is covered with granulations of a rounded form, which give to these scales their splendid and varied colours; the second plate is covered with silk, forming sometimes curious designs; the third plate, viz., that which is applied to the membrane of the wing, has the peculiar property of reflecting colours the most brilliant and the most varied, although the surface of the scales visible to the eye is often dull and colourless."Supposing," says M. Bernard Deschamps, "that a painter was possessed of colours rich enough to represent on canvas with all their splendour, gold, silver, the opal, the ruby, the sapphire, the emerald, and the other precious stones which the East produces, that with these colours he formed all the shades which could result from their combination, one might affirm without the chance of contradiction, that he would have none of these colours and of their various shades, whatever might be the number, which could not be discovered by the microscope on part of the scales of the Lepidoptera, which Nature has been pleased to conceal from our gaze."Fig. 134.—Portion of the wing of a MothFig. 134.—Portion of the wing of a Moth (Saturnia pavonia major), magnified.Each of these scales adheres to the membrane of the wing by a small tube, which is solidly fixed to it. Réaumur has called our attention to the admirable arrangement of these scales, which are disposed like those of fish, that is to say, in such a manner that those of a row shall partially overlap those in the following one.InFig. 134, representing a portion of the wing of theSaturnia pavonia major, magnified, which we borrow from Réaumur's Memoir, the scales are arranged in rows; isolated scales, and the points where other scales were fixed before they were taken off, are represented.The membranous frame which supports the coloured scales of butterflies and moths is well worth a moment's consideration. It consists of two membranes intimately united by their interior surfaces,and divided into many distinct parts by horny, fistulous threads, more or less ramified, which seem intended to support the two membranes mentioned above, and which branch out from the base to the edge of the wing. Their number, counting from the exterior edge, is not always the same in the upper and lower wings. It varies from eight to twelve.With its large and light wings, the butterfly can fly for a long time. But this flight is not in the least regular; it is not made in a straight line. When the insect has to go some distance, it flies alternately up and down. The line it takes is composed of an infinity of zig-zags, going up and down, and from right to left. This irregularity of flight saves the little insect from falling a prey to birds. "I saw one day with pleasure," says Réaumur, "a sparrow which pursued in the air a butterfly for nearly ten minutes without being able to catch it. The flight of the bird was nevertheless considerably more rapid than that of the butterfly, but the butterfly was always higher or lower than the place to which the bird flew, and where it thought it would catch it."But let us leave the wings to pass on to the other parts of the butterfly. These other parts are thethoraxor chest, the body orabdomen, and thehead.The thorax is solidly put together, so as to bear the movements of the wings and legs. These latter are composed, as in other insects, of five parts: the coxa, the trochanter, the thigh, the shank, and the tarsus.Many butterflies have all their six legs of equal length. In others, the two fore legs are very small, and are not suited for walking. In others, again, they are rudimentary, being deprived of hooks, very hairy, and applied on to the front of the breast.Fig. 135.—Leg of Butterfly armed with hooks.Fig. 135.—Leg of Butterfly armed with hooks.Fig. 136.—Leg not suitable for walking.This difference of structure may be seen in Figs.135and136, one of which represents, after Réaumur, a leg unsuited for walking, very hairy, and terminated in a sort of brush resembling the tail on a tippet; and the other a leg furnished with hooks.The abdomen has the form of an elongated, or—in the majority of species—an almost cylindrical oval. It is composed of five segments, each formed of an upper and a lower ring, joined together by a membrane. The first are larger than the others, and generally overlap the edges, which gives to this part of the body the power of dilating considerably.We must dwell longer on the head. It is generally rounded, compressed in front, longer than it is broad, and furnished with fine or scaly hairs. The important organs of which this part is the seat are the eyes, the antennæ, the palpi, and the proboscis or trunk.The eyes are more or less spherical, surrounded by hairs, and composed of innumerable facettes. Colours are seen on these as various as those of the rainbow. But the colour which serves as a base to all, is black in some, grey in others; then again there are different gold or bronze colours of the greatest splendour, inclining sometimes to red, sometimes to yellow, sometimes to green. On the compound eye of a butterfly as many as 17,325 facettes have been counted. Simple eyes, or stemmata, are moreover observed in certain species, and are generally more or less hidden by scales.The antennæ are situated near the upper rim or border of each eye. Réaumur has pointed out six principal shapes. One terminates in a littleknob, and belongs to the butterflies. The others are variously shaped, and belong to the moths. Some are prismatic, or like beading. And lastly, others are shaped like feathers. We represent, inFig. 137, the different forms of the antennæ, which Réaumur collected together in plates 8 and 9 of his fifth Memoir.[46]The palpi are four in number, two maxillary and two labial. The first are generally excessively small; one can only ascertain their existence by the aid of a strong magnifying glass: the second are in general very apparent, straight, cylindrical, covered with scales, and formed of three joints, of which the last is often very small and sometimes very pointed. They also sometimes bristle with stiff or silky hairs.The trunk is placed exactly between the two eyes. As long as the butterfly does not want to take nourishment, the trunk remains rolled in a spiral. Some are so short, that they scarcely make one turn and a half or two turns; some larger sized make three turns and a half or four turns; lastly, some very long are curled as many as eight or ten times.This is how the butterfly makes use of its trunk: When flutteringaround a flower, it will very soon settle on or quite close to it. The trunk is then brought forward entirely or almost entirely unrolled; very soon afterwards it is almost straightened, then directed downwards, and plunged into the flower. Sometimes the insect draws it out a moment after, curves it, twists it a little, and sometimes even curls it partially up. Immediately it straightens it again, to plunge it a second time into the same flower. It repeats the same manœuvre seven or eight times, and then flies on to another flower.Fig. 137.—Antennæ of Lepidoptera.Fig. 137.—Antennæ of Lepidoptera.This trunk, of which the butterfly makes such good use, is composed of two filaments more or less long, horny, concave in their interior surfaces, and fastened together by their edges. When cuttransversely, one sees, according to Réaumur,[47]that the interior is composed of three small rings. Consequently, there are three canals in the trunk: one central, the other two lateral (Fig. 138). Are all these three used to conduct the juice of flowers into the butterfly's body? Réaumur has made some very interesting observations on this subject, by observing a moth which was sucking a lump of sugar whilst its portrait was being taken.Fig. 138.—Section of a Butterfly's Trunk, after Réaumur.Fig. 138.Section of a Butterfly's Trunk, after Réaumur."I held in one hand," says Réaumur, "a powerful magnifying glass, which I brought near to that part of the trunk I wished to examine; I was sometimes half a minute, or nearly a minute, without perceiving anything, after which I saw clearly a little column of liquid mounting quickly along the whole length of the trunk. Often this column appeared to be intersected by little balls, which seemed to be globules of air which had been drawn up with the liquid."This liquid ascended thus during three or four seconds, and then ceased. At the end of an interval of a greater number of seconds, or sometimes after an interval as short, I saw some fresh liquid mounting up along the trunk. But it was straight up the middle of the trunk that it seemed to ascend."The Author of Nature has given to insects means of working, which, though very simple, we cannot divine, and which often we are not able even to perceive. Whilst I was observing the trunk of our butterfly, between the columns of liquid which I saw ascending, there were, but more rarely, times when I saw, on the contrary, liquid descending from the base of the trunk to the point. The descending liquid occupied half or two-thirds of the tube. It was no longer difficult to perceive how the butterfly is able to nourish itself on honey, the thickest syrup, and even the most solid sugar. The fluid it sends down is probably very liquid; it drives against the sugar, moistens, and dissolves it. The butterfly pumps this liquid up again when it is charged with sugar, and conducts it along as far as the base of its trunk, and beyond it."The life of the perfect insect is generally very short. Like nearly all other insects, they die as soon as they have propagated their species. The female lays her eggs, which vary in shape, on the plantwhich is to nourish her progeny. The colour is also very various, and passes through all sorts of shades. At the moment they are laid, many are covered with a gummy substance, insoluble in water, which serves to stick them on the plant.In some species the mother lays her eggs on the trunks of trees, and covers them with down or with the hairs which clothe her abdomen, so as to preserve them from cold and damp. She may also hide them entirely under a whitish foamy substance. Some do not lay more than a hundred eggs; others lay some thousands.To bring the history of the Lepidoptera to an end, it only remains for us to give a sketch of their classification, and to point out some species remarkable, either on account of their beauty or their utility.We see during the day butterflies flying in our gardens, in meadows full of flowers, or in the alleys of woods. Towards evening, at the sombre hour of twilight, the stroller is sometimes surprised to see pass near him large moths, with a heavy and unequal flight; or, if we go into a garden on a beautiful calm summer's night, bearing a light, we see a crowd of moths flying from all parts towards it.It is on account of these different hours at which the Lepidoptera show themselves, that naturalists for a long time divided them into diurnal, crepuscular, and nocturnal. This division was simple, convenient, and seemed founded on Nature. Unfortunately, thenightfliers of the old authors do not all fly by night: some species, classed by the old naturalists among the crepuscular, or nocturnal, show themselves in the very middle of the day, seeking their food in the hottest rays of the sun. In the regions near the poles they appear during the day, and in other countries they are more or less friends of the twilight.So as not to multiply methodical divisions, we will confine ourselves to classing the Lepidoptera into two sections.The first section contains thosewhich fly during the day, which have club-shaped antennæ, and which have their four wings entirely free, and standing perpendicularly[48]when the insect is at rest. They are called Butterflies, or Rhopalocera. This section is divided into a number of families, which comprise many genera. We will content ourselves with calling the attention of the reader to some of the most remarkable of these groups, and to those species which, either on account of their beauty or abundance, strike, or ought to strike, the attention of every one.Fig. 139.—Swallow-tailed ButterflyFig. 139.—Swallow-tailed Butterfly (Papilio machaon).In the family of thePapilionidi, we will mention the generaPapilio, to which belong the Swallow-tailed Butterfly (Papilio machaon),Papilio podalirius, &c., andParnassius, of which we will noticeParnassius Apollo, andParnassius Mnemosyne.Fig. 140.—Larva and Chrysalis of Papilio machaon.The swallow-tailed butterfly is found plentifully in the fens of Cambridgeshire, and Norfolk and Suffolk, and very commonly in the environs of Paris. It is seen from the beginning of May till towards the middle of June; then from the end of July till September. It frequents gardens, woods, and, above all, fields of lucerne. It is easily taken when settled, particularly at sunset.This is one of the largest and the most beautiful of the European butterflies. The wings are variegated with yellow and black; the eyes, antennæ, and trunk are black. The body is yellow on the sides and underneath, and black above. The front wings have rounded edges; the hind ones, on the contrary, are notched, and one of these notches is prolonged into a sort of tail. The first are black, spotted and striped with yellow; the second have their upper part and middle yellow, with some touches only of black. Near the margin is a broad black band, dusted with blue; lastly, six yellow spots in the form of a crescent run along the border, and end in a magnificent eye of a reddish colour, bordered with blue.Fig. 141.—Papilio Alexanor.The caterpillar of this species is large, smooth, and of a beautiful light green, with a transverse black band on each ring. These bands are sprinkled with orange spots. It lives on the fennel, carrot, and other Umbelliferæ. If teased, it thrusts from the first ring afterthe head a fleshy, orange-coloured tentacle. The chrysalis, attached to a stalk of grass, is sometimes light green, sometimes greyish.In the low Alps, on the plains near the environs of Digne and Barcelonette, is found in the months of May and July thePapilio Alexanor(Fig. 141), and in Corsica and Sardinia is found thePapilio hospiton, a rare species, nearly related to our swallow-tailed butterfly, but which we will here content ourselves with mentioning.Fig. 142.—The scarce Swallow-tailed ButterflyFig. 142.—The scarce Swallow-tailed Butterfly (Papilio podalirius).ThePapilio podalirius(Fig. 142) is in form very analogous toPapilio machaon. It is of a rather pale yellow colour, marked with black, as if singed. The lower wings have tails longer and narrower than those of the latter, and are magnificently ornamented with blue crescent-shaped spots and an orange-coloured eye bordered below with blue. This beautiful species is not rare at Montmorency, at Ile-Adam, and at St. Germain. It is said to have been taken in England, and is called the scarce Swallow-tail, but its capture is considered as very questionable. It appears for the first time at the endof April, and for the second in July and August. TheParnassius Apollo(Fig. 143), is a beautiful butterfly, which appears in June and July, and is found commonly enough in the Alps, the Pyrenees, and the Cévennes. Its wings are of a yellowish white. The upper part of the fore wings presents five nearly round black spots; the base and the costa, or front edge, of these wings are sprinkled with black atoms. The upper part of the hind wings presents two eyes of a vermilion red, the inner border furnished with whitish hairs amply dotted with black, and marked towards the extremity with two black spots. The under part of the fore wings is very similar to the upper. But the under part of the hind wings presents four red spots bordered by black, forming a transverse band near the base. The body is black, furnished with russety hairs, and the antennæ white, with the club black.Fig. 143.—Parnassius Apollo.The larva of the Apollo lives on saxifrages. To affect its transformation it surrounds itself with a slight network of silk in which are confined one or more leaves. This caterpillar is thick, smooth, cylindrical, and covered with small slightly hairy warts, and ornamented on the first ring with a fleshy tentacle in the shape of a Y. The chrysalis is conical, sprinkled over with a bluish efflorescence resembling the bloom on a plum. TheParnassius Mnemosyneis found in the month of June in the mountains of Dauphiné, in Switzerland, Sicily, Hungary, Sweden, and in the Pyrenees.In the family of thePieridiwe will mention many species remarkable in different ways, such asPieris cratægi, the black-veined White,Pieris brassicæ, the Cabbage Butterfly,Pieris napi,Pieriscallidice,Anthocharis cardamines, the Orange-tip,Rhodocera(Gonepteryx)rhamni, andColias edusa, or Clouded-yellow.Pieris cratægiis white both above and below; the veins only of the wings are black, and become a little broader at the edge of the upper wings. These black veins on a rather transparent white ground make this butterfly resemble a gauze veil, hence its French name,le gaze. It flies in spring and summer in meadows and gardens, but is not generally common in England. In the first volume of his "Travels in the North of Russia," Pallas relates that he saw insects of this species flying in great numbers in the environs of Winofka, and that he at first took them for flakes of snow. ThePieris cratægifixes itself at sunset on flowers, where it is easily taken by the hand. During the day, on the contrary, it is difficult to catch. The larva, black at first, afterwards assumes short yellow and white hairs, but it varies much. They live in companies, under a silky web, in which they pass the winter. The leaves of the hawthorn, the sloe, the cherry tree, and of many other fruit trees, serve them for food. The pupa, yellow or white, and sometimes of both colours with little stripes and spots of black, is angular and terminated in front by a blunt point.Fig. 144.—Pieris brassicæ.Fig. 144.—Pieris brassicæ.Fig. 145.—Caterpillar and Chrysalis of Pieris brassicæ.Fig. 145.—Caterpillar and Chrysalis of Pieris brassicæ.ThePieris brassicæ(Fig. 144), or Cabbage Butterfly, is perhaps the commonest of all butterflies. From the beginning of spring till the end of autumn one sees it flying about everywhere, in the gardens, sometimes near and almost in the interior of towns. It is of a dull white, spotted and veined with black, and it can be seen at a long distance, when flitting from flower to flower, in a meadow or garden. And so children wage desperate war against this flying prey. The pursuit of the cabbage butterfly through the alleys ofparks, along the outskirts of woods, or on the green turf of meadows, is the first joy and the first passion of children in the country.The caterpillar (Fig. 145) is of a yellowish green, or rather greenish yellow, with three yellow longitudinal stripes separated by little black points, from each of which springs a whitish hair. It lives in groups on the cabbages in gardens, and on many other Cruciferæ. It is so voracious that it consumes in a day more than double its own weight, and, as it multiplies very quickly, commits great ravages in the vegetable garden. Its pupa (Fig. 145) is of an ashy white, spotted with black and yellow.ThePieris rapæ, or Small White Butterfly, differs but little from the preceding except in size. The caterpillar, which lives on the cabbage, turnip, mignonette, nasturtium, &c., is green, with three yellow lines. It does not do these much harm. In France it is calledle ver du cœur(the heartworm), because it penetrates in between leaves pressed closely together.ThePieris napi(Fig. 146), the Green-veined White, is very like the two preceding, but the wings, the lower one especially, have underneath broad veins, or bands, of a greenish colour. ThePieris callidice, the wings of which are white spotted with black, is common in the Alps of France, in Savoy and Switzerland, and in the Pyrenees. Its caterpillar lives near the regions of perpetual snow, on small cruciferous plants.Fig. 146.—Pieris napi.Fig. 147.—Anthocharis cardamines.The Orange-tips have, in the males, the extremity of the upper wings of a beautiful orange yellow. The rest of the wings is white in the only British species (Fig. 147), which is to be seen in meadowsfrom the end of April till the end of May, and sulphur-coloured in some other species.One species, extremely common, and which appears with but short interruption from the beginning of spring till the end of autumn, is the Brimstone Butterfly (Rhodocera[Gonepteryx]rhamni). The wings are a lemon yellow, with an orange-coloured spot in the middle of each, and the front border terminated in a series of very small iron-coloured spots. The body of the butterfly is black with silvery hairs.
Figs. 122, 123.—Cocoon of Pyralis corticalis (magnified, proper size 2/3 inch).Figs. 122, 123.—Cocoon of Pyralis corticalis (magnified, proper size 2/3 inch).
"When one sees," he says,[39]"an insect which, to construct a cocoon, begins by collecting together an infinite number of small plates of bark in order to compose of them two flat triangular blades; which, to gain its end, takes means that seem so roundabout, although they are the most suitable and the quickest it could adopt, one is very much tempted to consider such an insect, when one sees it thus acting, possessed of reason."
These two blades are at last transformed into a regular cocoon. The little animal, which is at the same time architect, cabinet-maker, and weaver, arranges it in such a way as to form a hollow cone, which it only remains for it to shut. Réaumur calls this sort of cocoon or shell,la coque en bateau, the boat-shaped cocoon. Some caterpillars weave cocoons of the same form with pure silk.
To bring this subject to an end, we will mention the industry of the Puss Moth (Dicranura vinula), and that of a smallTinea, which eats the barley stored away in our granaries.
The larva of the puss moth employs in the construction of its shell the wood of the tree on which it has lived. It bites it up, and mixing it with a glutinous fluid which it secretes from its mouth, reduces it to a sort of paste, which it then uses in the formation of an envelope, of such hardness that a knife can hardly cut into it.
TheTinealines the interior of a grain, of which it has previously devoured the contents, with a coating of silk, and divides it thus into two different chambers. In one of these it is to change into a pupa; in the other it places its excrement. And so the little careful architect constructs its house in such a manner as to find in it tranquillity, cleanliness, and comfort.
When caterpillars have not within their reach the materials they are in the habit of employing, like good workmen, they content themselves with what they can get. Réaumur reared a caterpillar which formed its cocoon of pieces of the paper of which the box was made in which it was imprisoned.
What an extraordinary condition! what a strange phase of vitality does the chrysalis present to us—a being occupying the middle state between the caterpillar and the perfect insect! How little does it resemble that which it previously was, and what it will become! In appearance it is scarcely a living being; it takes no nourishment, and has no digestive organs; can neither walk nor drag itself along, andhardly bends the joints of its body. The outside skin of the chrysalis appears to be cartilaginous; it is generally smooth, although some species have hairs scattered over their bodies.
We distinguish in chrysalides two opposite sides. The one is the insect's back, the other its under side. On the upper part of the latter (Fig. 124) we perceive various raised portions, formed and arranged like the bands round the heads of mummies; the back is plain and rounded in a great number of pupæ; but a great many others have on the upper part, along the edges which separate the two sides, little humps, eminences broader than they are thick, ending in a sharp point (Fig. 125).
The head of the angular pupæ terminates sometimes in two angular parts, which diverge from each other like two horns (Fig. 126). In some other cases they are curved into the form of a crescent. These appendages sometimes give to the pupa the appearance of a mask, especially as an eminence placed on the middle of the back is rather like a nose, and the small cavities may represent the eyes (Fig. 125).
The colours of angular pupæ attract our attention. Some are superbly tinted; they appear to be wrapped in silk and gold. Others have only spots of gold and silver on their belly or their back. All, however, have not this remarkable splendour, not these metallic spots. Some are green, yellow, and spotted with gold. Generally they are brown. Réaumur has shown that this golden colour is not due, as was thought for a long while, to colouring matter, but to a little whitish membrane, placed under the skin, which reflects the light through the thin outer pellicle, in such a manner as to produce theoptical illusion which imparts to the robe of the chrysalis the golden hues of a princess in grand costume.All is not gold that glitters, Réaumur proves literally, in the case of chrysalis.[40]
Let us add that the chrysalis remains thus superbly dressed as long as it is tenanted, but loses its colour as soon as the butterfly has quitted it.
The cone-shaped pupæ belong to the twilight and night-flying Lepidoptera, and to those butterflies whose caterpillars are onisciform, or in shape resembling a wood-louse. They are generally oval, rounded at the head, and more or less conical at the lower end. Their colour is generally of a uniform chestnut brown.
What a mystery is that which is accomplished in the transition from the chrysalis to the perfect state! Those great changes from the larva state to that of the pupa, and from the pupa to that of the imago, are accomplished with such rapidity, that the phenomena were looked on as sudden metamorphoses, like those related in mythology. It has been thought also that there was in these changes from one state to another a sort of resurrection. There is here neither sudden metamorphosis, nor, as we will show, resurrection. In fact, the chrysalis is a living being; it indeed shows its vitality by exterior movements. Under the old skin of a caterpillar about to moult, under the envelope which is soon to be cast off, the new integuments are being prepared.
Fig. 127.—Chrysalis of the large Tortoise-shell Butterfly (Vanessa polychloros), magnified, seen from the lower side.Fig. 127.Chrysalis of the large Tortoise-shell Butterfly (Vanessa polychloros), magnified, seen from the lower side.
Some days before the moult, split the caterpillar's skin, and you will find the skin which is to take its place already beneath. If, some days before the transformation of the caterpillar into a chrysalis, it is dissected, the rudiments of wings and antennæ may be discovered. If a chrysalis is examined on the outside, all the parts of the future insect can be distinguished under the skin: the wings, the legs, the antennæ, the proboscis, &c.; only, these parts are folded and packed away in such a manner that the chrysalis can make no use of them. It could not, moreover, make use of them on account of their incomplete development.Fig. 127shows, after Réaumur,[41]a chrysalis magnified and seen from its lower side, on which we observe:—a, the wings;b b, the antennæ;t, the trunk or proboscis.
There is a moment when these parts, pressed one against each other, and as it were swathed up like a mummy, are very easily seen, for they are, as we may say, laid bare. This moment is that inwhich the pupa has just quitted the caterpillar's skin. It is then still soft and tender. Its body is moistened with a liquid, which, drying rapidly, becomes opaque, coloured, and of a membranous consistency. The result is that the parts which did not cohere in the least when the chrysalis made its first appearance, are fastened together, so that although they could at first be seen, through a layer of transparent fluid, they are now hidden under a sort of veil or cloak. It is necessary to seize then the moment of the birth of the chrysalis, to observe it accurately.
On examining the pupa before the liquid which pervades these parts has had time to dry, it resembles the perfect insect. All the exterior parts which belong to the imago can be distinguished. One recognises the head, which is then resting on the thorax; the two eyes and the antennæ (Fig. 128), which are brought forward like two ribbons; the wings also brought over the thorax, but these are separated artificially in the drawing we have given after Réaumur;[42]and lastly in the space left between the wings, the six legs, and the body of the insect.
Fig. 128.—Chrysalis of the Large Tortoise-shell Butterfly (Vanessa polychloros) whose different parts have been opened before they were fastened down.Fig. 128.—Chrysalis of the Large Tortoise-shell Butterfly (Vanessa polychloros) whose different parts have been opened before they were fastened down.(a, wings;b b, antennæ;t, trunk, or proboscis.)
To sum up: the pupa, when it approaches the period for being hatched is only a swaddled butterfly. Directly it has strength enough to rid itself of its wrapping, the insect frees itself from its fetters; it flies away, brilliant and free, and its many-coloured wings glitter in the sun.
The duration of the pupa state is variable, according to the species and the temperature. Réaumur placed in a hot-house, in the month of January, some pupæ which, in the ordinary course of things, would not have been hatched till the month of May, and a fortnight afterwards the imagos had appeared. On the other hand, he shut up some pupæ in an ice-house during the whole of a summer, and thus retarded their being hatched by a whole year. The influence of the temperature on the period of emerging, and, consequently, the influence of the seasons on the length of this period, are completely brought to light by these experiments.[43]
We will now see how the insect delivers itself from the last skin. To quit the pupa case is not so laborious an operation as it was for the same insect to quit the caterpillar's skin. This is because the pupa case is drier; it does not adhere to every part of the body, and is brittle. Those insects which are enclosed in a cocoon free themselves of the pupa envelope in the cocoon itself. To witness the last operation, the cocoon may be opened, and the pupa drawn out of it with care. If it is then placed in a box, the metamorphosis may be observed. To study this last evolution more at his ease, Réaumur covered a large extent of the wall of his study with pupæ of theVanessa polychlorosand other species.
When the parts of the body of the insect have attained a certain degree of solidity within the envelope, it has no great difficulty in making the thin and friable membrane which surrounds it split in different places. If it even distends itself or moves, a small opening will be made in the dried skin. If the movements persist, theopening increases in size, and very soon allows the imago to emerge.
Fig. 129.Moth just emerged.
Fig. 130.Moth whose wings are folded up.
It is on the middle of the upper part of the thorax that the envelope begins to split. The split extends over the middle of the forehead and back. The pieces of the thorax open, separate themselves from the other parts to which they were fixed, and the insect can take advantage of the opening which is made, and escape. Little by little also it advances its head. The head is the first out of the old skin, and the insect sets itself entirely free.
This occupies rather a long time; for we must remember that, under the pupal envelope, its legs, its antennæ, its wings, and many other parts, are enclosed in special cases. These peculiar circumstances show that the animal has much trouble and must employ some time in setting free all the parts.
At last our prisoner has come out of its narrow cell, and is delivered from its old covering. What poet can describe to us the sensations of this charming and frail creature which has just risen from the tomb, and for the first time is enjoying the splendid light of day, the radiant sky, and the flowers redolent with delicious perfumes, which are inviting it to kiss and caress them!
The wings strike one most. They are very small at the time of birth.
Fig. 129represents, after Réaumur,[44]a moth at the moment in which it has just emerged from the pupa. But at the end of a short period the wings become developed; only they are wrinkled, asFig. 130, given by Réaumur, represents.
Réaumur having taken between his fingers a very short wing of a butterfly which was just hatched, drew it about gently in all directions. He succeeded thus in giving it the whole extent it would have assumed naturally. According to Réaumur the wing of a butterfly just born, which appears so small, is really already provided with all its parts, only it is folded and re-folded on itself. He supposes that what his hands did to lengthen the butterfly's wings, is done naturallyby the liquids which are contained in the insect which has just emerged, and whose wings are no longer confined in their cases. At the time of its birth the wings are flat and thick; as they grow, little by little they spread themselves out and become curled up. When they are completely developed and flattened the wings become firm and hard imperceptibly, and this firmness extends at the same time to the whole of the body.
Figs.131and132, borrowed, like the preceding, from the 14th Memoir of Réaumur (sur la transformation des chrysalides en papillons), show the states through which the wings of the same moth pass, before they are thoroughly developed.
Those pupæ enclosed in cocoons free themselves entirely or in part from their old skin, in the shell itself; but the imago is still a prisoner. It has broken through a first enclosure; it must open itself a way through the second. How does it manage to bore through the often very solid walls of this second prison, so as to regain its liberty? Réaumur states that in the Lackey Moth (Bombyx neustria) the head is the only instrument of which the insect makes use in opening a passage, the compound eyes then acting like files. These files cut the very fine threads of which the cocoon is composed, and as soon as the end of the cocoon is pierced through, the insect uses its thorax like a wedge, to enlarge the hole. It very soon manages to get its two front legs out, fixes itself by them on to the outside, and little by little emerges from its prison.
The Perfect Insect.
Who does not admire the extraordinary splendour, the vivacity, the prodigious variety of colours of these brilliant inhabitants of the air? Some amateurs have devoted to the purchase of certain butterflies large sums of money. "Diamonds," says Réaumur on the subject, "have perhaps beauties no more real than those of a butterfly's wings; but they have a beauty which is more acknowledged by the world in general, and which is more recognised in commerce." The essential character of butterflies and moths makes them very easily recognisable among all other insects. All have four wings, which are covered with scales, that communicate to them the brilliant colours with which they are decorated. It is these scales which adhere to the fingers when we seize one of these charming creatures.
Fig. 133.—Different forms of the scales of Butterflies, after Réaumur.Fig. 133.—Different forms of the scales of Butterflies, after Réaumur.
For a long time this dust was thought to be formed of very small feathers, but Réaumur showed that it is composed of little scales. Their form varies singularly, as we may see inFig. 133, borrowed from the Memoirs of Réaumur,[45]which represents the different forms of the scales which cover the wings of Lepidoptera. M. BernardDeschamps has closely studied them. According to this naturalist, they are composed of three membranes, or plates, superposed one on the other, of which the first is covered with granulations of a rounded form, which give to these scales their splendid and varied colours; the second plate is covered with silk, forming sometimes curious designs; the third plate, viz., that which is applied to the membrane of the wing, has the peculiar property of reflecting colours the most brilliant and the most varied, although the surface of the scales visible to the eye is often dull and colourless.
"Supposing," says M. Bernard Deschamps, "that a painter was possessed of colours rich enough to represent on canvas with all their splendour, gold, silver, the opal, the ruby, the sapphire, the emerald, and the other precious stones which the East produces, that with these colours he formed all the shades which could result from their combination, one might affirm without the chance of contradiction, that he would have none of these colours and of their various shades, whatever might be the number, which could not be discovered by the microscope on part of the scales of the Lepidoptera, which Nature has been pleased to conceal from our gaze."
Fig. 134.—Portion of the wing of a MothFig. 134.—Portion of the wing of a Moth (Saturnia pavonia major), magnified.
Each of these scales adheres to the membrane of the wing by a small tube, which is solidly fixed to it. Réaumur has called our attention to the admirable arrangement of these scales, which are disposed like those of fish, that is to say, in such a manner that those of a row shall partially overlap those in the following one.
InFig. 134, representing a portion of the wing of theSaturnia pavonia major, magnified, which we borrow from Réaumur's Memoir, the scales are arranged in rows; isolated scales, and the points where other scales were fixed before they were taken off, are represented.
The membranous frame which supports the coloured scales of butterflies and moths is well worth a moment's consideration. It consists of two membranes intimately united by their interior surfaces,and divided into many distinct parts by horny, fistulous threads, more or less ramified, which seem intended to support the two membranes mentioned above, and which branch out from the base to the edge of the wing. Their number, counting from the exterior edge, is not always the same in the upper and lower wings. It varies from eight to twelve.
With its large and light wings, the butterfly can fly for a long time. But this flight is not in the least regular; it is not made in a straight line. When the insect has to go some distance, it flies alternately up and down. The line it takes is composed of an infinity of zig-zags, going up and down, and from right to left. This irregularity of flight saves the little insect from falling a prey to birds. "I saw one day with pleasure," says Réaumur, "a sparrow which pursued in the air a butterfly for nearly ten minutes without being able to catch it. The flight of the bird was nevertheless considerably more rapid than that of the butterfly, but the butterfly was always higher or lower than the place to which the bird flew, and where it thought it would catch it."
But let us leave the wings to pass on to the other parts of the butterfly. These other parts are thethoraxor chest, the body orabdomen, and thehead.
The thorax is solidly put together, so as to bear the movements of the wings and legs. These latter are composed, as in other insects, of five parts: the coxa, the trochanter, the thigh, the shank, and the tarsus.
Many butterflies have all their six legs of equal length. In others, the two fore legs are very small, and are not suited for walking. In others, again, they are rudimentary, being deprived of hooks, very hairy, and applied on to the front of the breast.
This difference of structure may be seen in Figs.135and136, one of which represents, after Réaumur, a leg unsuited for walking, very hairy, and terminated in a sort of brush resembling the tail on a tippet; and the other a leg furnished with hooks.
The abdomen has the form of an elongated, or—in the majority of species—an almost cylindrical oval. It is composed of five segments, each formed of an upper and a lower ring, joined together by a membrane. The first are larger than the others, and generally overlap the edges, which gives to this part of the body the power of dilating considerably.
We must dwell longer on the head. It is generally rounded, compressed in front, longer than it is broad, and furnished with fine or scaly hairs. The important organs of which this part is the seat are the eyes, the antennæ, the palpi, and the proboscis or trunk.
The eyes are more or less spherical, surrounded by hairs, and composed of innumerable facettes. Colours are seen on these as various as those of the rainbow. But the colour which serves as a base to all, is black in some, grey in others; then again there are different gold or bronze colours of the greatest splendour, inclining sometimes to red, sometimes to yellow, sometimes to green. On the compound eye of a butterfly as many as 17,325 facettes have been counted. Simple eyes, or stemmata, are moreover observed in certain species, and are generally more or less hidden by scales.
The antennæ are situated near the upper rim or border of each eye. Réaumur has pointed out six principal shapes. One terminates in a littleknob, and belongs to the butterflies. The others are variously shaped, and belong to the moths. Some are prismatic, or like beading. And lastly, others are shaped like feathers. We represent, inFig. 137, the different forms of the antennæ, which Réaumur collected together in plates 8 and 9 of his fifth Memoir.[46]
The palpi are four in number, two maxillary and two labial. The first are generally excessively small; one can only ascertain their existence by the aid of a strong magnifying glass: the second are in general very apparent, straight, cylindrical, covered with scales, and formed of three joints, of which the last is often very small and sometimes very pointed. They also sometimes bristle with stiff or silky hairs.
The trunk is placed exactly between the two eyes. As long as the butterfly does not want to take nourishment, the trunk remains rolled in a spiral. Some are so short, that they scarcely make one turn and a half or two turns; some larger sized make three turns and a half or four turns; lastly, some very long are curled as many as eight or ten times.
This is how the butterfly makes use of its trunk: When flutteringaround a flower, it will very soon settle on or quite close to it. The trunk is then brought forward entirely or almost entirely unrolled; very soon afterwards it is almost straightened, then directed downwards, and plunged into the flower. Sometimes the insect draws it out a moment after, curves it, twists it a little, and sometimes even curls it partially up. Immediately it straightens it again, to plunge it a second time into the same flower. It repeats the same manœuvre seven or eight times, and then flies on to another flower.
Fig. 137.—Antennæ of Lepidoptera.Fig. 137.—Antennæ of Lepidoptera.
This trunk, of which the butterfly makes such good use, is composed of two filaments more or less long, horny, concave in their interior surfaces, and fastened together by their edges. When cuttransversely, one sees, according to Réaumur,[47]that the interior is composed of three small rings. Consequently, there are three canals in the trunk: one central, the other two lateral (Fig. 138). Are all these three used to conduct the juice of flowers into the butterfly's body? Réaumur has made some very interesting observations on this subject, by observing a moth which was sucking a lump of sugar whilst its portrait was being taken.
Fig. 138.—Section of a Butterfly's Trunk, after Réaumur.Fig. 138.Section of a Butterfly's Trunk, after Réaumur.
"I held in one hand," says Réaumur, "a powerful magnifying glass, which I brought near to that part of the trunk I wished to examine; I was sometimes half a minute, or nearly a minute, without perceiving anything, after which I saw clearly a little column of liquid mounting quickly along the whole length of the trunk. Often this column appeared to be intersected by little balls, which seemed to be globules of air which had been drawn up with the liquid.
"This liquid ascended thus during three or four seconds, and then ceased. At the end of an interval of a greater number of seconds, or sometimes after an interval as short, I saw some fresh liquid mounting up along the trunk. But it was straight up the middle of the trunk that it seemed to ascend.
"The Author of Nature has given to insects means of working, which, though very simple, we cannot divine, and which often we are not able even to perceive. Whilst I was observing the trunk of our butterfly, between the columns of liquid which I saw ascending, there were, but more rarely, times when I saw, on the contrary, liquid descending from the base of the trunk to the point. The descending liquid occupied half or two-thirds of the tube. It was no longer difficult to perceive how the butterfly is able to nourish itself on honey, the thickest syrup, and even the most solid sugar. The fluid it sends down is probably very liquid; it drives against the sugar, moistens, and dissolves it. The butterfly pumps this liquid up again when it is charged with sugar, and conducts it along as far as the base of its trunk, and beyond it."
The life of the perfect insect is generally very short. Like nearly all other insects, they die as soon as they have propagated their species. The female lays her eggs, which vary in shape, on the plantwhich is to nourish her progeny. The colour is also very various, and passes through all sorts of shades. At the moment they are laid, many are covered with a gummy substance, insoluble in water, which serves to stick them on the plant.
In some species the mother lays her eggs on the trunks of trees, and covers them with down or with the hairs which clothe her abdomen, so as to preserve them from cold and damp. She may also hide them entirely under a whitish foamy substance. Some do not lay more than a hundred eggs; others lay some thousands.
To bring the history of the Lepidoptera to an end, it only remains for us to give a sketch of their classification, and to point out some species remarkable, either on account of their beauty or their utility.
We see during the day butterflies flying in our gardens, in meadows full of flowers, or in the alleys of woods. Towards evening, at the sombre hour of twilight, the stroller is sometimes surprised to see pass near him large moths, with a heavy and unequal flight; or, if we go into a garden on a beautiful calm summer's night, bearing a light, we see a crowd of moths flying from all parts towards it.
It is on account of these different hours at which the Lepidoptera show themselves, that naturalists for a long time divided them into diurnal, crepuscular, and nocturnal. This division was simple, convenient, and seemed founded on Nature. Unfortunately, thenightfliers of the old authors do not all fly by night: some species, classed by the old naturalists among the crepuscular, or nocturnal, show themselves in the very middle of the day, seeking their food in the hottest rays of the sun. In the regions near the poles they appear during the day, and in other countries they are more or less friends of the twilight.
So as not to multiply methodical divisions, we will confine ourselves to classing the Lepidoptera into two sections.
The first section contains thosewhich fly during the day, which have club-shaped antennæ, and which have their four wings entirely free, and standing perpendicularly[48]when the insect is at rest. They are called Butterflies, or Rhopalocera. This section is divided into a number of families, which comprise many genera. We will content ourselves with calling the attention of the reader to some of the most remarkable of these groups, and to those species which, either on account of their beauty or abundance, strike, or ought to strike, the attention of every one.
Fig. 139.—Swallow-tailed ButterflyFig. 139.—Swallow-tailed Butterfly (Papilio machaon).
In the family of thePapilionidi, we will mention the generaPapilio, to which belong the Swallow-tailed Butterfly (Papilio machaon),Papilio podalirius, &c., andParnassius, of which we will noticeParnassius Apollo, andParnassius Mnemosyne.
Fig. 140.—Larva and Chrysalis of Papilio machaon.
The swallow-tailed butterfly is found plentifully in the fens of Cambridgeshire, and Norfolk and Suffolk, and very commonly in the environs of Paris. It is seen from the beginning of May till towards the middle of June; then from the end of July till September. It frequents gardens, woods, and, above all, fields of lucerne. It is easily taken when settled, particularly at sunset.
This is one of the largest and the most beautiful of the European butterflies. The wings are variegated with yellow and black; the eyes, antennæ, and trunk are black. The body is yellow on the sides and underneath, and black above. The front wings have rounded edges; the hind ones, on the contrary, are notched, and one of these notches is prolonged into a sort of tail. The first are black, spotted and striped with yellow; the second have their upper part and middle yellow, with some touches only of black. Near the margin is a broad black band, dusted with blue; lastly, six yellow spots in the form of a crescent run along the border, and end in a magnificent eye of a reddish colour, bordered with blue.
Fig. 141.—Papilio Alexanor.
The caterpillar of this species is large, smooth, and of a beautiful light green, with a transverse black band on each ring. These bands are sprinkled with orange spots. It lives on the fennel, carrot, and other Umbelliferæ. If teased, it thrusts from the first ring afterthe head a fleshy, orange-coloured tentacle. The chrysalis, attached to a stalk of grass, is sometimes light green, sometimes greyish.
In the low Alps, on the plains near the environs of Digne and Barcelonette, is found in the months of May and July thePapilio Alexanor(Fig. 141), and in Corsica and Sardinia is found thePapilio hospiton, a rare species, nearly related to our swallow-tailed butterfly, but which we will here content ourselves with mentioning.
Fig. 142.—The scarce Swallow-tailed ButterflyFig. 142.—The scarce Swallow-tailed Butterfly (Papilio podalirius).
ThePapilio podalirius(Fig. 142) is in form very analogous toPapilio machaon. It is of a rather pale yellow colour, marked with black, as if singed. The lower wings have tails longer and narrower than those of the latter, and are magnificently ornamented with blue crescent-shaped spots and an orange-coloured eye bordered below with blue. This beautiful species is not rare at Montmorency, at Ile-Adam, and at St. Germain. It is said to have been taken in England, and is called the scarce Swallow-tail, but its capture is considered as very questionable. It appears for the first time at the endof April, and for the second in July and August. TheParnassius Apollo(Fig. 143), is a beautiful butterfly, which appears in June and July, and is found commonly enough in the Alps, the Pyrenees, and the Cévennes. Its wings are of a yellowish white. The upper part of the fore wings presents five nearly round black spots; the base and the costa, or front edge, of these wings are sprinkled with black atoms. The upper part of the hind wings presents two eyes of a vermilion red, the inner border furnished with whitish hairs amply dotted with black, and marked towards the extremity with two black spots. The under part of the fore wings is very similar to the upper. But the under part of the hind wings presents four red spots bordered by black, forming a transverse band near the base. The body is black, furnished with russety hairs, and the antennæ white, with the club black.
Fig. 143.—Parnassius Apollo.
The larva of the Apollo lives on saxifrages. To affect its transformation it surrounds itself with a slight network of silk in which are confined one or more leaves. This caterpillar is thick, smooth, cylindrical, and covered with small slightly hairy warts, and ornamented on the first ring with a fleshy tentacle in the shape of a Y. The chrysalis is conical, sprinkled over with a bluish efflorescence resembling the bloom on a plum. TheParnassius Mnemosyneis found in the month of June in the mountains of Dauphiné, in Switzerland, Sicily, Hungary, Sweden, and in the Pyrenees.
In the family of thePieridiwe will mention many species remarkable in different ways, such asPieris cratægi, the black-veined White,Pieris brassicæ, the Cabbage Butterfly,Pieris napi,Pieriscallidice,Anthocharis cardamines, the Orange-tip,Rhodocera(Gonepteryx)rhamni, andColias edusa, or Clouded-yellow.Pieris cratægiis white both above and below; the veins only of the wings are black, and become a little broader at the edge of the upper wings. These black veins on a rather transparent white ground make this butterfly resemble a gauze veil, hence its French name,le gaze. It flies in spring and summer in meadows and gardens, but is not generally common in England. In the first volume of his "Travels in the North of Russia," Pallas relates that he saw insects of this species flying in great numbers in the environs of Winofka, and that he at first took them for flakes of snow. ThePieris cratægifixes itself at sunset on flowers, where it is easily taken by the hand. During the day, on the contrary, it is difficult to catch. The larva, black at first, afterwards assumes short yellow and white hairs, but it varies much. They live in companies, under a silky web, in which they pass the winter. The leaves of the hawthorn, the sloe, the cherry tree, and of many other fruit trees, serve them for food. The pupa, yellow or white, and sometimes of both colours with little stripes and spots of black, is angular and terminated in front by a blunt point.
Fig. 144.—Pieris brassicæ.Fig. 144.—Pieris brassicæ.
Fig. 145.—Caterpillar and Chrysalis of Pieris brassicæ.Fig. 145.—Caterpillar and Chrysalis of Pieris brassicæ.
ThePieris brassicæ(Fig. 144), or Cabbage Butterfly, is perhaps the commonest of all butterflies. From the beginning of spring till the end of autumn one sees it flying about everywhere, in the gardens, sometimes near and almost in the interior of towns. It is of a dull white, spotted and veined with black, and it can be seen at a long distance, when flitting from flower to flower, in a meadow or garden. And so children wage desperate war against this flying prey. The pursuit of the cabbage butterfly through the alleys ofparks, along the outskirts of woods, or on the green turf of meadows, is the first joy and the first passion of children in the country.
The caterpillar (Fig. 145) is of a yellowish green, or rather greenish yellow, with three yellow longitudinal stripes separated by little black points, from each of which springs a whitish hair. It lives in groups on the cabbages in gardens, and on many other Cruciferæ. It is so voracious that it consumes in a day more than double its own weight, and, as it multiplies very quickly, commits great ravages in the vegetable garden. Its pupa (Fig. 145) is of an ashy white, spotted with black and yellow.
ThePieris rapæ, or Small White Butterfly, differs but little from the preceding except in size. The caterpillar, which lives on the cabbage, turnip, mignonette, nasturtium, &c., is green, with three yellow lines. It does not do these much harm. In France it is calledle ver du cœur(the heartworm), because it penetrates in between leaves pressed closely together.
ThePieris napi(Fig. 146), the Green-veined White, is very like the two preceding, but the wings, the lower one especially, have underneath broad veins, or bands, of a greenish colour. ThePieris callidice, the wings of which are white spotted with black, is common in the Alps of France, in Savoy and Switzerland, and in the Pyrenees. Its caterpillar lives near the regions of perpetual snow, on small cruciferous plants.
The Orange-tips have, in the males, the extremity of the upper wings of a beautiful orange yellow. The rest of the wings is white in the only British species (Fig. 147), which is to be seen in meadowsfrom the end of April till the end of May, and sulphur-coloured in some other species.
One species, extremely common, and which appears with but short interruption from the beginning of spring till the end of autumn, is the Brimstone Butterfly (Rhodocera[Gonepteryx]rhamni). The wings are a lemon yellow, with an orange-coloured spot in the middle of each, and the front border terminated in a series of very small iron-coloured spots. The body of the butterfly is black with silvery hairs.