Chapter M: P. Huber is the only modern author that appears to have been witness to (2)

Besides the golden species of the genus _Lampyris_, all of which are probably more or less luminous, another insect of the beetle tribe, _Elater noctilucus_, is endowed with the same property, and that in a much higher degree. This insect, which is an inch long, and about one-third of an inch broad, gives out its principal light from two transparent eye-like tubercles placed upon the thorax; but there are also two luminous patches concealed under the elytra, which are not visible except when the insect is flying, at which time it appears adorned with four brilliant gems of the most beautiful golden-blue lustre: in fact, the whole body is full of light, which shines out between the abdominal segments when stretched. The light emitted by the two thoracic tubercles alone is so considerable, that the smallest print may be read by moving one of these insects along the lines; and in the West India islands, particularly in St. Domingo, where they are very common, the natives were formerly accustomed to employ those living lamps, which they called _cucuij_, instead of candles, in performing their evening household occupations. In travelling at night, they used to tie one to each great toe; and in fishing and hunting, required no other flambeau.--_Pietro Martire's Decades of the New World_, _quoted in Madoc_, p. 543. Southey has happily introduced this insect in his "Madoc," as furnishing the lamp by which Coatel rescued the British hero from the hands of the Mexican priests.

"She beckon'd and descended, and drew out,
From underneath her vest, a cage, or net
It rather might be called, so fine the twigs
Which knit it, where, confined, two fire-flies gave
Their lustre. By that light did Madoc first
Behold the features of his lovely guide."

Pietro Martire tells us, that cucuij serve the natives of the Spanish West India islands not only instead of candles, but as extirpators of the gnats, which are a dreadful pest to the inhabitants of the low grounds. They introduce a few fire-flies, to which the gnats are a grateful food, into their houses, and by means of these "commodious hunters," are soon rid of the intruders. "How they are a remedy (says this author) for so great a mischiefe, it is a pleasant thing to hear. Hee who understandeth that he has those troublesome guestes (the gnattes) at home, diligently hunteth after the cucuij. Whoso wanteth cucuij, goeth out of the house in the first twilight of the night, carrying a burning fire-brande in his hande, and ascendeth the next hillock, that the cucuij may see it, and hee swingeth the fire-brande about, calling Cucuie aloud, and beating the ayre with often calling out, Cucuie, Cucuie." He goes on to observe, that the simple people believe the insect is attracted by their invitations; but that, for his part, he is rather inclined to think that the fire is the magnet. Having obtained a sufficient number of cucuij, the beetle-hunter returns home, and lets them fly loose in the house, where they diligently seek the gnats about the beds and the faces of those asleep, and devour them.--_Martire ubi supr. Colonies_, i. 128. These insects are also applied to purposes of decoration. On certain festival-days, in the month of June, they are collected in great numbers, and tied all over the garments of young people, who gallop through the streets on horses similarly ornamented, producing on a dark evening the effect of a large moving body of light. On such occasions, the lover displays his gallantry by decking his mistress with these living gems.--_Walton's Present State of the Spanish Colonies._ And according to P. Martire, "many wanton wilde fellowes" rub their faces with "the flesh of a killed cucuij," as boys with us use phosphorus, "with purpose to meet their neighbours with a flaming countenance," and derive amusement from their fright.

Besides _Elater noctilucus_, _E. ignitus_, and several others of the same genus, are luminous: not fewer than twelve species of this family are described by Illiger in the Berlin Naturalist Society's Magazine.

The brilliant nocturnal spectacle presented by these insects to the inhabitants of the countries where they abound, cannot be better described than in the language of the poet above referred to, who has thus related its first effect upon British visitors of the new world:

"------------------------sorrowing we beheld
The night come on: but soon did night display
More wonders than it veil'd; innumerable tribes
From the wood-cover swarm'd, and darkness made
Their beauties visible; one while they stream'd
A bright blue radiance upon flowers that clos'd
Their gorgeous colours from the eye of day;
Now motionless and dark, eluding search,
Self-shrouded; and anon starring the sky,
Rose like a shower of fire."

If we are to believe Mouffet, (and the story is not incredible,) the appearance of the tropical fire-flies on one occasion led to a more important result than might have been expected from such a cause. He tells us, that when Sir Thos. Cavendish and Sir John Dudley first landed in the West Indies, and saw in the evening an infinite number of moving lights in the woods, which were merely these insects, they supposed that the Spaniards were advancing upon them, and immediately betook themselves to their ships: a result as well entitling the elatera to a commemoration feast, as a similar good office by the land-crabs of Hispaniola, which, as the Spaniards tell, (and the story is confirmed by an anniversary _Fiesta de los Cangrejos_,) by their clattering being mistaken for the sound of Spanish cavalry close upon their heels, in like manner scared away a body of English invaders from the city of St. Domingo.--_Walton's Hispaniola_, i. 39.

An anecdote less improbable, perhaps, and certainly more ludicrous, is related by Sir James Smith, of the effect of the first sight of the Italian fire-flies upon some Moorish ladies, ignorant of such appearances. These females had been taken prisoners at sea, and, until they could be ransomed, lived in a house in the outskirts of Genoa, where they were frequently visited by the respectable inhabitants of the city; a party of whom, on going one evening, were surprised to find the house closely shut up, and their Moorish friends in the greatest grief and consternation. On inquiring into the cause, they ascertained that some of the Lampyris Italica had found their way into the dwelling, and that the ladies within had taken it into their heads that these brilliant guests were no other than the troubled spirits of their relations; and some time elapsed before they could be divested of this idea. The common people in Italy have a superstition respecting these insects somewhat similar, believing that they are of a spiritual nature, and proceed out of the graves; and hence carefully avoid them.--_Tour on the Continent_, 2d ed. iii. 85.

The insects hitherto adverted to have been beetles, or of the order _Coleoptera_. But, besides these, a genus in the order _Hemiptera_, called _Fulgora_, includes several species, which emit so powerful a light, as to have obtained in English the generic appellation of lantern-flies. Two of the most conspicuous of this tribe are the _F. lanternaria_ and _F. candelaria_; the former a native of South America, the latter of China. Both, as indeed is the case with the whole genus, have the material which diffuses their light included in a hollow subtransparent projection of the head. In _F. candelaria_ this projection is of a subcylindrical shape, recurved at the apex, above an inch in length, and the thickness of a small quill. We may easily conceive, as travellers assure us, that a tree studded with multitudes of these living sparks, some at rest and others in motion, must during the night have a superlatively splendid appearance.

In _F. lanternaria_, which is an insect two or three inches long, the snout is much larger and broader, and more of an oval shape, and sheds a light, the brilliancy of which transcends that of any other luminous insect. Madam Merian informs us, that the first discovery she made of this property caused her no small alarm. The servants had brought her several of these insects, which by day-light exhibited no extraordinary appearance, and she inclosed them in a box till she should have an opportunity of drawing them, placing them upon a table in her lodging-room. In the middle of the night the confined insects made such a noise as to awake her, and she opened the box, the inside of which, to her great astonishment, appeared all in a blaze; and in her fright letting it fall, she was not less surprised to see each of the insects apparently on fire. She soon, however, divined the cause of this unexpected phenomenon, and re-inclosed her brilliant guests in their place of confinement. She adds, that the light of one of these fulgora was sufficiently bright to read a newspaper by. Another species, _F. pyrrhorynchus_, is described by Donovan, in his Insects of India; of which the light, though from a smaller snout than that of _F. lanternaria_, must assume a more splendid and striking appearance, the projection being of a rich deep purple from the base to near the apex, which is of a fine transparent scarlet; and these tints will of course be imparted to the transmitted light.

With regard to the immediate source of the luminous properties of these insects, Mr. Macartney, to whom we are indebted for the most recent investigation on the subject, has ascertained, that in the common glow-worm, and in _Elater noctilucus_ and _ignitus_, the light proceeds from masses of a substance not generally differing, except in its yellow colour, from the interstitial substance _corps graisseux_, of the rest of the body, closely applied underneath those transparent parts of the insects' skin which afford the light. In the glowworm, besides the last-mentioned substance, which, when the season for giving light is passed, is absorbed, and replaced by the common interstitial substance, he observed on the inner side of the last abdominal segment two minute oval sacks, formed of an elastic spirally-wound fibre, similar to that of the trachea, containing a soft yellow substance, of a closer texture than that which lines the adjoining region, and affording a more permanent and brilliant light. This light he found to be less under the control of the insect than that from the adjoining luminous substance, which it has the power of voluntarily extinguishing, not by retracting it under a membrane, as Carradori imagined, but by some inscrutable change which depends upon its will: and when the latter substance was extracted from living glowworms, it afforded no light, while the two sacks in like circumstances shone uninterruptedly for several hours. Mr. Macartney conceives, from the radiated structure of interstitial substance surrounding the oval yellow masses immediately under the transparent spot in the thorax of _Elater noctilucus_, and the subtransparency of the adjoining crust, that the interstitial substance in this situation has also the property of shining; a supposition which, if De Geer and other authors be correct in stating, that this insect has two luminous patches over its elytra, and that the incisures between the abdominal segments shine when stretched, may probably be extended to the whole of the interstitial substance of its body.

With respect to the remote cause of the luminous property of insects, philosophers are considerably divided in opinion. The disciples of modern chemistry have in general, with Dr. Darwin, referred it to the slow combustion of some combination of phosphorus secreted from their fluids by an appropriate organization, and entering into combination with the oxygen supplied in respiration. This opinion is very plausibly built upon the ascertained existence of phosphoric acid as an animal secretion; the great resemblance between the light of phosphorus in slow combustion, and animal light; the remarkably large spiracula in glowworms; and upon the statement, that the glowworm is rendered more brilliant by the application of heat and oxygen gas, and is extinguished by cold and by hydrogen and carbonic acid gases. From these last facts, Spallanzani was led to regard the luminous matter as a compound of hydrogen and carburetted hydrogen gas. Carradori having found that the luminous portion of the belly of the Italian glowworm, _lampyris Italica_, shone in vacuo, in oil, in water, and when under other circumstances where the presence of oxygen gas was precluded,--with Brugnatelli, ascribed the property in question to the imbibition of light, separated from the food or air taken in the body, and afterwards secreted in a sensible form.[15] Lastly, Mr. Macartney having ascertained, by experiment, that the light of a glowworm is not diminished by immersion in water, or increased by the application of heat; that the substance affording it, though poetically employed for lighting the fairies' tapers,[16] is incapable of inflammation, if applied to the flame of a candle or red-hot iron; and when separated from the body, exhibits no sensible heat on the thermometer's being applied to it,--rejects the preceding hypothesis as unsatisfactory, but without substituting any other explanation; suggesting, however, that the facts he observed are more favourable to the supposition of light being a quality of matter, than a substance.

Which of these opinions is the more correct, is left for future philosophers to decide.

The general use of this singular provision is not much more satisfactorily ascertained than its nature. It is conjectured that it may be a means of defence against its enemies. In different kinds of insects, however, it may probably have a different object. Thus in the lantern-flies, (_Fulgora_,) whose light precedes them, it may act the part that their name imports, enable them to discover their prey, and to steer themselves safely in the night. In the fire-flies, (_Elater_,) if we consider the infinite numbers, that in certain climates and situations present themselves every where in the night, it may distract the attention of their enemies, or alarm them. And in the glowworm, since their light is usually more brilliant in the female, it is most probably intended to conduct the sexes to each other.

Thine is an unobtrusive blaze,
Content in lowly shades to shine;
And much I wish, while yet I gaze,
To make thy modest merit mine!
_Mrs. Opie._

CHAP. XXVIII.

CURIOSITIES RESPECTING INSECTS.--(_Continued._)

_The Flea--On the Duration of the Life of a Flea--The Louse._

THE FLEA,--has two eyes and six feet, fitted for leaping; the feelers are like threads; the rostrum is inflected, setaceous, and armed with a sting; and the belly is compressed. Fleas bring forth eggs, which they deposit on animals that afford them a proper food. Of these eggs are hatched white worms of a shining pearl colour, which feed on the scurfy substance of the cuticle, the downy matter gathered in the piles or folds of clothes, or other similar substances. In a fortnight they come to a tolerable size, and are very lively and active; and, if at any time disturbed, they suddenly roll themselves into a kind of ball. Soon after this, they come to creep, after the manner of silk-worms, with a very swift motion. When arrived at their size, they hide themselves as much as possible, and spin a silken thread out of their mouth, wherewith they form themselves a small round bag, or case, white within as paper, but without always dirty, and fouled with dust. Here, after a fortnight's rest, the animalcule bursts out, transformed into a perfect flea, leaving its exuviæ in the bag. While it remains in the bag, it is milk-white till the second day before its eruption, when it becomes coloured, grows hard, and gets strength; so that, upon its first delivery, it springs nimbly away. The flea is covered all over with black, hard, and shelly scales or plates, which are curiously jointed, and folded over each other in such a manner as to comply with all the nimble motions of the creature. These scales are finely polished, and beset about the edges with short spikes, in a very beautiful and regular order. Its neck is finely arched, and resembles the tail of a lobster: the head is also very extraordinary; for from the snout-part of it proceed the two fore-legs, and between these is placed the piercer, or sucker, with which it penetrates the skin to get its food. Its eyes are very large and beautiful, and it has two short horns, or feelers. It has four other legs, joined all at the breast. These, when it leaps, fold short, one within another; and then, exerting their spring all at the same instant, they carry the creature to a surprising distance. The legs have several joints, are very hairy, and terminate in two long and hooked sharp claws. The piercer, or sucker, of the flea, is lodged between its fore-legs, and includes a couple of darts or lancets, which, after the piercer has made an entrance, are thrust farther into the flesh, to make the blood flow from the adjacent parts, and occasion that round red spot, with a hole in the centre of it, vulgarly called a flea-bite.

This piercer, its sheath opening sidewise, and the two lancets within it, are very difficult to be seen, unless the two fore-legs, between which they are hid, be cut off close to the head; for the flea rarely puts out its piercer, except at the time of feeding, but keeps it folded inwards; and the best way of seeing it, is by cutting off first the head, and then the fore-legs, and then it is usually seen thrust out in convulsions. By keeping fleas in a glass tube corked up at both ends, but so as to admit fresh air, their several actions may be observed. They may be thus seen to lay their eggs, &c. They do not lay their eggs all at once, but by ten or twelve in a day, for several days successively, which eggs will be afterwards found to hatch successively, in the same order. The flea may easily be dissected in a drop of water; and thus the stomach and bowels, with their peristaltic motion, may be discovered very plainly, with the veins and arteries, though minute beyond all conception. This bloodthirsty insect, which fattens at the expense of the human species, prefers the more delicate skin of women, but preys neither upon epileptic persons, nor upon the dead or dying. It loves to nestle in the fur of dogs, cats, and rats. The nests of river-swallows are sometimes plentifully stored with them. Fleas are apterous, walk but little, but leap to a height equal to two hundred times that of their own body. This amazing motion is performed by means of the elasticity of their feet, the articulations of which are so many springs. Thus it eludes, with surprising agility, the pursuit of the person on whom it riots. Mercurial ointment, brimstone, a fumigation with the leaves of pennyroyal, or fresh-gathered leaves of that plant, sewed up in a bag, and laid in the bed, are remedies pointed out as destructive of fleas.

In the Athenian Oracle, a lady desires to know whether fleas have stings, or whether they only suck or bite, when they draw blood from the body? To which an ingenious author returns the following humorous answer:

"Not to trouble you, madam, with the Hebrew or Arabic name of a flea, or to transcribe Bochart's learned dissertations on the little animal, we shall, for your satisfaction, give such a description thereof as we have yet been able to discover.--

"Its skin is of a lovely deep red colour, most neatly polished, and armed with scales, which can resist any thing but fate, and your ladyship's unmerciful fingers: the neck of it is exactly like the tail of a lobster, and, by the assistance of those strong scales it is covered with, springs backwards and forwards much in the same manner, and with equal violence: it has two eyes on each side of its head, so pretty, that I would prefer them to any, madam, but yours; and which it makes use of to avoid its fate, and flee from its enemies, with as much nimbleness and success, as your sex manage those fatal weapons, lovely basilisks as you are, for the ruin of your adorers. Nature has provided it six substantial legs, of great strength, and incomparable agility, jointed like a cane, covered with large hairs, and armed each of them with two claws, which appear of a horny substance, more sharp than lancets, or the finest needle you have in your needle-book. It was a long while before we could discover its mouth, which, we confess, we have not yet so exactly perceived as we could wish, the little bashful creature always holding up its two fore-feet before it, which it uses instead of a fan or mask, when it has no mind to be known; and we were forced to be guilty of an act both uncivil and cruel, without which we could never have resolved your question. We were obliged to unmask this modest one, and cut off its two fore-legs to get to the face; which being performed, though it makes our tender hearts, as well as yours, almost bleed to think of it, we immediately discovered what your ladyship desired, and found Nature had given it a strong proboscis, or trunk, as a gnat or muschetto, though much thicker and stouter, with which we may very well suppose it penetrates your fair hand, feasts itself on the nectar of your blood, and then, like a little faithless fugitive of a lover, skips away, almost invisibly, nobody knows whither."

We close our remarks on this well-known insect, with the following interesting particulars on the DURATION OF THE LIFE OF A FLEA; by Borrichius; from the Acts of Copenhagen.--"Pliny represents to us a Greek philosopher, whose chief occupation, for several years together, was to measure the space skipped over by fleas. Without giving in to such ridiculous researches, I can relate an anecdote, which chance discovered to me in regard to this insect.

"Being sent for to attend a foreign lady, who was greatly afflicted with the gout, and having staid, by her desire, to dine with her, she bade me take notice of a flea on her hand. Surprised at such discourse, I looked at the hand, and saw indeed a plump and pampered flea sucking greedily, and kept fast to it by a little gold chain. The lady assured me, she had nursed and kept the little animal, at that time, full six years, with exceeding great care, having fed it twice every day with her blood; and when it had satisfied its appetite, she put it up in a little box, lined with silk. In a month's time, being recovered from her illness, she set out from Copenhagen with her flea; but having returned in about a year after, I took an opportunity of waiting upon her, and, among other things, asked after her little insect. She answered me with great concern, that it died through the neglect of her waiting-woman. What I found remarkable in this story was, that the lady, being attacked by chronical pains in her limbs, had recourse in France to very powerful medicines during six weeks; and all this time the flea had not ceased to feed upon her blood, imbued with the vapours, and yet was not the worse for it."

THE LOUSE.--This insect has six feet, two eyes, and a sort of sting in the mouth; the feelers are as long as the thorax; and the belly is depressed and sublobated. It is an oviparous animal. They are not peculiar to man alone, but infest other animals, as quadrupeds and birds, and even fishes and vegetables; but these are of peculiar species on each animal, according to the particular nature of each, some of which are different from those which infest the human body. Nay, even insects are infested with vermin, which feed on and torment them. Several kinds of beetles are subject to lice, but particularly that kind called by way of eminence the lousy beetle. The lice on this are very numerous, and will not be shook off. The earwig is often infested with lice, just at the setting on of its head: these are white and shining, like mites, but they are much smaller; they are round-backed, flat-bellied, and have long legs, particularly the foremost pair. Snails of all kinds, but especially the large naked sorts, are very subject to lice; which are continually seen running about them, and devouring them. Numbers of little red lice, with a very small head, and in shape resembling a tortoise, are often seen about the legs of spiders, and they never leave the animal while he lives; but if he be killed, they almost instantly forsake him. A sort of whitish lice is found on humblebees; they are also found upon ants; and fishes are not less subject to them than other animals. Kircher tells us, that he found lice also on flies, and M. de la Hire has given a curious account of the creature which he found on the common fly. Having occasion to view a living fly with the microscope, he observed on its head, back, and shoulders, a great number of small animals crawling very nimbly about, and often climbing up the hairs which grow at the origin of the fly's legs. He with a fine needle took up one of these, and placed it before the microscope used to view the animalcules in fluids. It had eight legs, four on each side; these were not placed very distant from each other, but the four towards the head were separated by a small space from the four towards the tail. The feet were of a particular structure, being composed of several fingers, as it were, and fitted for taking fast hold of any thing, but the two nearest the head were also more remarkable in this particular than those near the tail; the extremities of the legs for a little way above the feet were dry, and void of flesh, like the legs of birds, but above this part they appeared plump and fleshy. It had two small horns upon its head, formed of several hairs arranged closely together; and there were some other clusters of hairs by the side of these horns, but they had not the same figure; and towards the origin of the hind-legs there were two other such clusters of hairs, which took their origin at the middle of the back. The whole creature was of a bright yellowish red; the legs, and all the body, except a large spot in the centre, were perfectly transparent. In size, he computed it to be about 1/4000th part of the head of the fly; and he observes, that such kind of vermin are rarely found on flies.

The louse which infests the human body, makes a very curious appearance through a microscope. It has such a transparent shell or skin, that we are able to discover more of what passes within its body, than in most other living creatures. It has naturally three divisions, the head, the breast, and the tail part. In the head appear two fine black eyes, with a horn that has five joints, and is surrounded with hairs standing before each eye; and from the end of the nose, or snout, there is a pointed projecting part, which serves as a sheath or case to a piercer, or sucker, which the creature thrusts into the skin to draw out the blood and humours which are its destined food; for it has no mouth that opens in the common way. This piercer, or sucker, is judged to be seven hundred times smaller than a hair, and is contained in another case within the first, and can be drawn in or thrust out at pleasure. The breast is very beautifully marked in the middle; the skin is transparent, and full of little pits; and from the under part of it proceed six legs, each having five joints, and their skin all the way resembling shagreen, except at the ends, where it is smoother. Each leg is terminated by two claws, which are hooked, and are of an unequal length and size. These it uses as we would a thumb and middle finger; and there are hairs between these claws, as well as all over the legs. On the back part of the tail there may be discovered some ring-like divisions, and a sort of marks which look like the strokes of a rod on the human skin; the belly looks like shagreen, and towards the lower end it is very clear, and full of pits: at the extremity of the tail there are two semicircular parts, all covered over with hairs. When the louse moves its legs, the motion of the muscles, which all unite in an oblong dark spot in the middle of the breast, may be distinguished perfectly; and so may the motion of the muscles of the head, when it moves its horns. We may likewise see the various ramifications of the veins and arteries, which are white, with the pulse regularly beating in the arteries. The peristaltic motion of the intestines may be distinctly seen, from the stomach down to the anus.

If one of these creatures, when hungry, be placed on the back of the hand, it will thrust its sucker into the skin, and the blood which it sucks may be seen passing in a fine stream to the fore part of the head; where, falling into a roundish cavity, it passes again in a fine stream to another circular receptacle in the middle of the head; from thence it runs through a small vessel to the breast, and then to a gut which reaches to the hinder part of the body, where, in a curve, it turns again a little upward in the breast and gut; the blood is moved without intermission with great force, especially in the former, where it occasions a surprising contraction.

In the upper part of the crooked ascending gut above-mentioned, the propelled blood stands still, and seems to undergo a separation, some of it becoming clear and waterish, while other black particles are pushed forward to the anus. If a louse is placed on its back, two bloody darkish spots appear; the larger in the middle of the body, the smaller towards the tail; the motions of which are followed by the pulsation of the dark bloody spot, in or over which the white bladder seems to lie. This motion of the systole and diastole is best seen when the creature begins to grow weak; and on pricking the white bladder, which seems to be the heart, it instantly dies. The lower dark spot is supposed to be the excrement.

CHAP. XXIX.

CURIOSITIES RESPECTING INSECTS.--(_Continued._)

In the vast, and the minute, we see
Th' unambiguous footsteps of a God,
Who gives its lustre to an insect's wing,
And wheels his throne upon the rolling worlds.
_Cowper._

THE APHIS.

This is an insect which has engaged the attention of naturalists for various reasons: their generation is equivocal, and their instinctive economy differs, in some respects, from that of most other animals. Linnæus defines the generic character of the aphis thus: beak inflected, sheath of five articulations, with a single bristle; antennæ setaceous, and longer than the thorax; either four erect wings, or none; feet formed for walking; posterior part of the abdomen usually furnished with two little horns. Geoffrey says, the aphides have two beaks, one of which is seated in the breast, the other in the head; this last extends to, and is laid upon, the base of the pectoral one, and serves, as that writer imagines, to convey to the head a part of that nourishment which the insect takes or sucks in by means of the pectoral beak.

Gmelin enumerates about seventy species, all of which, and doubtless many others, are found in different parts of Europe. They infest an endless variety of plants; and it is believed that each species is particularly attached to one kind of vegetable only: hence each sort has been hitherto named after the individual species or genus of plants on which it feeds; or if that could not be ascertained, that on which it had been found; for some species are rather uncommon and little known, though others are infinitely too numerous. The aphides are sufficiently known by the indiscriminate term of plant-lice; they abound with a sweet and grateful moisture, and are therefore eagerly devoured by ants, the larvæ coccinellæ, and many other creatures, or they would become, very probably, more destructive to the whole vegetable creation than any other race of insects known. If Bonnet was not the first naturalist (as is generally acknowledged) who discovered the mysterious course of generation in the aphides, or, as he calls them, pucerons, his experiments, together with those of his countryman, Trembley, tended at least to confirm, in a most satisfactory manner, the almost incredible circumstances respecting it, that an aphis, or puceron, brought up in the most perfect solitude from the moment of its birth, in a few days will be found in the midst of a numerous family; and that if the experiment be again repeated on one of the individuals of this family, a second generation will multiply like its parent; and the like experiment may be many times repeated with the same effect.

The history of aphides has also been very copiously treated upon by Dr. Richardson, in a paper printed in the 41st vol. of the Philosophical Transactions, and by the late ingenious Mr. Curtis, in the 6th vol. of the Transactions of the Linnæan Society. The tenor of Dr. Richardson's remarks is briefly this: The great variety of species which occur in the insects now under consideration, may render an inquiry into their particular natures not a little perplexing; but by reducing them under their proper genus, the difficulty is considerably diminished. We may reasonably suppose all the insects comprehended under any distinct genus, to partake of one general nature; and by diligently examining any particular species, we may thence gain some insight into the nature of all the rest. With this view, Dr. Richardson chose out of the various sorts of aphides, the largest of those found on the rose-tree; not only as its size makes it more conspicuous, but as there are few of so long duration. This sort appears early in the spring, and continues late in autumn; while several are limited to a much shorter term, in conformity to the different trees and plants whence they draw their nourishment.

If, at the beginning of February, the weather happens to be so warm as to make the buds of the rose-tree swell and appear green, small aphides are frequently to be found on them, though not larger than the young ones in summer, when first produced. It will be found, that those aphides which appear only in spring, proceed from small black oval eggs, which were deposited on the last year's shoot; though it happens that, when the insects make too early an appearance, the greater part suffer from the sharp weather that usually succeeds, by which means the rose-trees are some years freed from them. The same kind of animal is then at one time of the year viviparous, and at another oviparous. Those aphides which withstand the severity of the weather, seldom come to their full growth before the month of April, at which time they usually begin to breed, after twice casting off their exuvia, or outward covering.

When they first come from the parent, they are enveloped in a thin membrane, having the appearance of an oval egg; these egg-like appearances adhere by one extremity to the mother, while the young ones contained in them extend to the other, and by that means gradually draw the ruptured membrane over the head and body to the hind-feet. Being thus suspended in the air, the insect soon frees itself from the membrane in which it was confined, and, after its limbs are a little strengthened, is set down on some tender shoots, and left to provide for itself. In the spring months there appear on the rose-trees but two generations of aphides, including those which proceed immediately from the last year's eggs; the warmth of the summer adds so much to their fertility, that no less than five generations succeed each other in the interval. One is produced in May, which casts off their covering; while the months of June and July each supply two more, which cast off their coverings three or four times, according to the different warmth of the season. This frequent change of their outward coat is the more extraordinary, because it is repeated more often when the insects come the soonest to their growth, which sometimes happens in ten days, when they have had plenty of warmth and nourishment. Early in the month of June, some of the third generation, which were produced about the middle of May, after casting off the last covering, discover four erect wings, much longer than their bodies; and the same is observable in all the succeeding generations which are produced during the summer months, but, like all the others, without any diversity of sex: for some time before the aphides come to their full growth, it is easy to distinguish which will have wings, by a remarkable fulness of the breast, which in the others is hardly to be distinguished from the body. When the last covering is ejected, the wings, which were before folded up in a very narrow compass, are gradually extended in a surprising manner, till their dimensions are at last very considerable. The increase of these insects in the summer time is so very great, that by wounding and exhausting the tender shoots, they would frequently suppress all vegetation, had they not many enemies to restrain them.

Notwithstanding these insects have a numerous tribe of enemies, they are not without their friends, if those maybe considered as such, who are officious in their attendance, for the good things they expect to reap thereby. The ant and bee are of this kind, collecting the honey in which the aphides abound, but with this difference, that the ants are constant visitors, the bee only when flowers are scarce; the ants will suck in the honey while the aphides are in the act of discharging it; the bees only collect it from the leaves on which it has fallen. In the autumn, three more generations of aphides are produced, two of which generally make their appearance in the month of August, and the third before the middle of September. The two first differ in no respect from those which are found in summer, but the third differs greatly from all the rest.

Though all the aphides which have hitherto appeared were female, in this generation several male insects are found, but not by any means so numerous as the females. The females have, at first, the same appearance as those of the former generations, but in a few days their colour changes from a green to a yellow, which is gradually converted into an orange before they come to their full growth; they differ also, in another respect, from those which occur in summer, for all these yellow females are without wings. The male insects are, however, still more remarkable, their outward appearance readily distinguishing them from this and all other generations. When first produced, they are not of a green colour like the rest, but of a reddish brown, and have afterwards a dark line along the back; they come to their full growth in about three weeks, and then cast off their last covering, the whole insect being, after this, of a bright yellow colour, the wings only excepted, but after this change they become a deeper yellow, and, in a very few hours, of a dark brown, if we except the body, which is something lighter coloured, and has a reddish cast. Where there are a number crowded together, they of course interfere with each other, in which case they will frequently deposit their eggs on other parts of the branches. It is highly probable that the aphides derive considerable advantages by living in society: the reiterated punctures of a great number of them may attract a larger quantity of nutritious juices to that part of the tree or plant where they have taken up their abode.

The observations of Mr. Curtis, on the aphides, are chiefly intended to shew that they are the principal cause of blights in plants, and the sole cause of the honey-dew. He therefore calls this insect the aphis, or blighter; and after observing, that, in point of numbers, the individuals of the several species composing it surpass those of any other genus in the country, speaks thus, in general terms, of the whole tribe.--"These insects live entirely on vegetables. The loftiest tree is no less liable to their attacks, than the most humble plant. They prefer the young shoots on account of their tenderness, and, on this principle, often insinuate themselves into the very heart of the plant, and do irreparable mischief before they are discovered. But, for the most part, they beset the foliage, and are always found on the under side of the leaf, which they prefer, not only on account of its being the most tender, but as it affords them protection from the weather, and various injuries to which they would otherwise be exposed. Sometimes the root is the object of their choice, which, from the nature of these insects, one would not, _á priori_, expect: yet I have seen the roots of lettuces thickly beset with them, and the whole crop rendered sickly and of little value; but such instances are rare. They seldom attach themselves to the bark of trees, like the aphis salicis, which being one of our largest species, and hence possessing superior strength, is enabled to penetrate a substance harder than the leaves themselves."

In the quality of the excrement voided by these insects, there is something wonderfully extraordinary. Were a person accidentally to take up a book, in which it is gravely asserted, that in some countries there were certain animals that voided liquid sugar, he would lay it down, regarding it as a fabulous tale, calculated to impose on the credulity of the ignorant; and yet such is literally the truth. Mr. Curtis collected some on a piece of writing-paper, from a brood of the aphis salicis, and found it to be as sweet as sugar; and observes, that were it not for the wasps, ants, flies, and other insects, that devour it as quickly as it is produced, it might, no doubt, be collected in considerable quantities, and, by the processes used with other saccharine juices, might be converted into the choicest sugar or sugar-candy. The sweetness of this excrementitious substance, the glossy appearance it gave the leaves it fell upon, and the swarms of insects this matter attracts, led him to imagine the honey-dew of plants was no other than this secretion, which further observation has since been fully confirmed; and not, as its name implies, a sweet substance falling from the atmosphere. On this opinion it is further remarked, that it neither falls from the atmosphere, nor issues from the plant itself, as is easily demonstrated. If it fell from the atmosphere, it would cover every thing it fell upon indiscriminately; whereas we never find it but on certain living plants and trees. We find it also on plants in stoves and greenhouses covered with glass. If it exuded from the plant, it would appear on all the leaves generally and uniformly; whereas its appearance is extremely irregular, not alike on any two leaves of the same tree or plant, some having none of it, and others being covered with it but partially.

It is probable that there never exists any honey-dew but where there are aphides; though such often pass unnoticed, being hidden on the under side of the leaf: and wherever honey is observable upon a leaf, aphides will be found on the underside of the leaf or leaves immediately above it, and under no other circumstance whatever. If by accident any thing should intervene between the aphides and the leaf next beneath them, there will be no honey-dew on that leaf: and thus he conceives it is incontrovertibly proved, that aphides are the true and only source of honey-dew.

Of the British species of aphides, one of the largest and most remarkable is the aphis salicis, which is found on the different kinds of willows. When bruised, these insects stain the fingers with red. Towards the end of September, multitudes of the full-grown insects of this species, both with and without wings, desert the willows on which they feed, and ramble over every neighbouring object in such numbers, that we can handle nothing in their vicinity without crushing some of them; while those in a younger or less advanced state, still remain in large masses upon the trees. Aphis rosæ is very frequent, during the summer months, on young shoots and buds of roses; it is of a bright green colour: the males are furnished with large transparent wings. Aphis vitis is most destructive to vines, as Aphis ulmi is to the elm-tree.

It is found that where the saccharine substance has dropped from aphides for a length of time, as from the aphis salicis in particular, it gives to the surface of the bark, foliage, &c. that sooty kind of appearance which arises from the explosion of gunpowder; it looks like, and is sometimes taken for, a kind of black mildew. In most seasons, the natural enemies of the aphis are sufficient to keep them in check, and to prevent them from doing essential injury to plants in the open air; but there are times, once perhaps in four, five, or six years, in which they are multiplied to such an excess, that the usual means of diminution fail in preventing them from doing irreparable injury to certain crops.

To prevent the calamities which would infallibly result from an accumulated multiplication of the more prolific animals, it has been ordained by the Author of nature, that such should be diminished by serving as food for others. On this principle, most animals of this kind have one or more natural enemies. The helpless aphis, which is the scourge of the vegetable kingdom, has to contend with many: the principal are the coccinella, the ichneumon aphidum, and the musca aphidivora. The greatest destroyer of the aphides is the coccinella, or common lady-bird.

During the winter, this insect secures itself under the bark of trees, and elsewhere. When the spring expands the foliage of plants, the female deposits her eggs on them in great numbers, from whence, in a short time, proceeds the larva, a small grub, of a dark lead-colour, spotted with orange. These may be observed in summer running pretty briskly over all kinds of plants; and, if narrowly watched, they will be found to devour the aphides wherever they find them. The same may be observed of the lady-bird, in its perfect state. Another most formidable enemy to the aphis, is a very minute, black, and slender ichneumon fly, which eats its way out of the aphis, leaving the dry inflated skin of the insect adhering to the leaf like a small pearl: such may always be found where aphides are in plenty. Different species of aphides are infested with different ichneumons. There is scarcely a division of nature, in which the musca, or fly, is not found: of these, one division, the aphidivora, feeds entirely on aphides.

Of the different species of aphidivorous flies, which are numerous, having mostly bodies variegated with transverse stripes, their females may be seen hovering over plants infested with aphides, among which they deposit their eggs on the surface of the leaf. The larva, or maggot, produced from such eggs, feeds, as soon as hatched, on the younger kinds of aphis, and, as it increases in size, attacks and devours those which are larger. The larva of the hemerolicus feeds also on the aphides, and deposits its eggs on the leaves of such plants as are beset with them. The earwig is likewise an enemy to them, especially such as reside in the curled leaves of fruit-trees, and the purses formed by certain aphides on the poplars and other trees. To these may be added the smaller soft-billed birds that feed on insects.

CHAP. XXX.

CURIOSITIES RESPECTING INSECTS.--(_Continued._)

_The Common House Fly--The Hessian Fly--The May Fly--The Vegetable
Fly--The Boat Fly--The Ephemeral Flies--Butterflies--Metamorphoses of
Insects--The Death-Watch._

What atom-forms of insect life appear!
And who can follow Nature's pencil here?
Their wings with azure, green, and purple gloss'd,
Studded with colour'd eyes, with gems emboss'd;
Inlaid with pearl, and mark'd with various stains
Of lively crimson through their dusky veins.
_Barbauld._

THE COMMON HOUSE FLY.

Gordart has reckoned up forty-eight varieties of the fly, without including them all in this enumeration. The multitude of these lively insects, which the first genial sunshine calls forth into life, has limits which the human eye is incapable of exploring. The female fly is easily distinguishable from the male: she is larger than the latter, fuller in the body, of a lighter colour, and, when she is nearly ready to deposit her eggs, the abdomen is so transparent, that they may be perceived lying on both sides, opposite to each other. Nature has instructed her not to deposit her eggs in dry, but in damp substances, which keep them from being dried up, and at the same time afford nourishment to the maggot or worm. The latter issues from the egg generally in twenty-four hours, but, in the sun, within twelve hours after it is laid. About half an hour before, annular circles become visible in the egg, an undulatory motion succeeds, the egg opens at the end, and the worm makes its appearance. Its entrance into the world is extremely tedious; for the three or four minutes taken by the worm to work its way out of the egg, are, for it, certainly so many days. It is endowed, on the other hand, with vital powers, which enable it to defy inconveniences which cost other animals their lives. Nothing but turpentine, the general destroyer of insects, kills it in half an hour. On the fourteenth or fifteenth day, it begins to prepare for its transformation into a nymph, and in this form appears at first of a light yellow, and afterwards of a dark red. You would take it, in this state, for some kind of seed, rather than for the habitation of a living creature. The change of the nymph into a fly requires as much time as the preceding transformation. A thrust with the head then bursts the prison in which it is confined, and the fly, perfectly formed, sallies forth. The sun hastens its birth, which is then the business of but a moment; but in unfavourable weather, this probably painful operation often takes four or five hours. The insect is now as perfect as its parents, and not to be distinguished from them. As soon as it issues from the nymph, it flies away; and only those are unable to use their wings immediately, which have the misfortune to come out in gloomy weather.

Leuwenhock reckons, that every fly has eight thousand hexagons or eyes, on each of the hemispheres composing its face, and consequently sixteen thousand on both. M. Von Gleichen, a German naturalist, observes, that the law of retaliation is in some measure established, in regard to these animals; for if they annoy us, they are in their turn persecuted by others. Small yellow insects, discovered by means of the magnifying glass, crawling among the hairs that grow on their bodies, are supposed to be destined for this purpose.

The fecundity of flies is prodigious. On this head, the last-mentioned naturalist has made the following calculation:--

A fly lays four times during the summer, each time
eighty eggs, which makes 320
Half of these are supposed to be females, so that each
of the four broods produces forty:
1. First eighth, or the forty females of the first
brood, also lay four times in the course of the
summer, which makes 12,800
The first eighth of these, or 1,600 females, three times 384,000
The second eighth, twice 256,000
The third and fourth eighth, at least one each 256,000
2. The second eighth, or the forty females of the second
brood, lay three times, the produce of which is 9,600
One sixth of these, or 1,600 females, three times 384,000
The second sixth, twice 256,000
The third sixth, once 128,000
3. The third eighth, or the forty females of the third
brood, lay twice, and produce 6,400
One fourth of these, or 1,600 females, lay twice more 256,000
4. The fourth eighth, or forty females of the fourth
brood, once 3,200
Half of these, or 1,600 females, at least once 128,000
---------
Total produce of a single fly, in one summer 2,080,320