MYRMELEON LIBELLULOIDES.

Plate XLVI. fig. 1.

Fabricius gives the Cape of Good Hope as the habitat of this species, referring not only to the present figure, but also to that given in Vol. 3. Plate 41. which is said by Drury to have been brought from Sierra Leone. This is the more inexcusable, because Drury expressly observed in a note, "There is a species found near the Cape of Good Hope very much like this, but distinctly different," although in the synoptical appendix to the third volume, he gives the large species from Sierra Leone as a variety of M. Libelluloides.

Plate XLVI. fig. 2.

Latreille, in his Genera Crustaceorum et Insectorum, Vol. 3. p. 199, after describing the genus Chauliodes belonging to the family HemerobiidÆ, observes, "Congenerica videntur insecta a Dom. Drury iconibus vivis expressa, tom. 1. Pl. 46. Fig. 2. 3." I have never seen the present species, but from the admirable accuracy of Moses Harris (by whom the figures were drawn) it is evident that the neuration of the wings of this species is identical with that of Myrmeleon, agreeing especially with the insect represented at Fig. 4. of this plate, and exhibiting the irregular longitudinal nerve below the subcostal nerve and the strong furcate nerve running along the middle of the wing; whilst, at the same time, the neuration is quite unlike that of Fig. 3. Hence I have no hesitation in placing this insect in the family MyrmeleonidÆ. It however disagrees with the genera of which that family is composed, viz. Myrmeleon, Linn. (Myrmecoleon, Burm.) Ascalaphus, Fabr. and Nymphes, Leach, in having bipectinated antennÆ, so that I have been compelled to establish a new genus for its reception. Can it be possible that, according to the not uncommon practice of the time, the specimen had been mended, and that pectinated antennÆ had been substituted in the stead of the ordinary ones of a Myrmeleon?

CHAULIODES VIRGINIENSIS.

Plate XLVI. fig. 3.

Drury has figured the wings as of an uniform colourless appearance, which induces me to consider that it may be distinct from the LinnÆan H. pectinicornis, that species being described by the great Swede with "signaturis nervisque fuscis albo subarticulatis." From the paleness of the present species it is evident that the transverse nerves connecting the longitudinal ribs of the wings in the typical species of this genus have been overlooked, especially as the longitudinal nerves are correctly represented. This genus and Corydalis, seem to form a connecting link between Hemerobius and Perla.

MYRMELEON AMERICANUM.

Plate XLVI. fig. 4.

---

LIBELLULIDÆ, Pl. 47 & 48.

All the insects represented in these two plates belong to the genus Libellula of LinnÆus, or the family of Dragon-flies, LibellulidÆ. When the original edition of this work was published, there was no English work in which the natural history and curious transformations of this tribe of insects were detailed. Our author, therefore, in order to supply the deficiency, published the following interesting series of observations upon the subject:—

"As I have not met with any English author who has given the natural history of the insects delineated in these two plates, I shall make no apology for its introduction; the frequent opportunities I have had of observing their mode of life and action, together with the many singular circumstances observable in both, being motives for its publication too powerful to be resisted.

"It is not easy to determine whether they should be ranked among the water insects, or those of the land, nor shall I attempt here to ascertain it; my present business being only to relate the several circumstances attending them during their respective states in which they are passing from the egg to the complete animal: and although these observations have been confined to our English ones, yet they so exactly agree and coincide with those of foreign countries, (as my correspondents have assured me), that their nature and behaviour appear to be just the same; so that what is observable in ours, is at the same time applicable to the whole genus wherever found.

"If we take a cursory view of the different ranks of animals that inhabit our globe, we shall hardly find one that can excite our wonder and astonishment more than this genus; nor is it from that general ignorance of the insect world, that reigns so strongly in these kingdoms, that I am emboldened to say this; but if we reflect that the beasts, birds, and reptiles are furnished with powers for living only in the air, and that even the amphibious tribes can perform the office of respiration only in that element: if we also consider that fishes, on the contrary, are unable to respire but in water, and when deprived of that must certainly perish, we cannot but conclude that all these animals are most wisely fitted with means and faculties for filling up the respective orders and ranks wherein they are placed. But let us cast our eyes on the subjects I am about to describe, and there behold a tribe of beings, who, as soon as they leave their eggs, subsist for a certain number of months, (I had almost said years), creeping and swimming in the liquid element; are there invested with organs and powers for existing and weathering out the utmost severity and intemperance of the winter; that afterwards as the spring and summer advances, and the period arrives when they are to appear in other forms, in the space of about half an hour those very organs and powers that before enabled them to live under water should be so entirely altered, the very natures and abilities of the creatures so changed as to permit them to quit their former element and place of residence, insomuch that all the remaining part of their lives is spent in the open air, furnished with wings, and flying about in the full glee of wanton liberty; that in a very few weeks after, having performed the business of generation, the same animals should die of mere old age, with their wings quite ragged and worn out, their strength exhausted, and all the powers of their bodies lost by a total imbecility and weakness, which but a little before enabled them to transport themselves through the air with the swiftness of a bird. If, I say, we reflect on all these circumstances, we cannot but allow them to be objects of a very extraordinary nature, and well adapted for leading the mind to the contemplation of their supreme Author, who has thought proper to exhibit to us these kind of insects, thus differing from almost all the animals in the creation.

"They have been variously named by different authors, owing perhaps to the time when they wrote, or the progress natural history had made in the world. Some have called them by the name of Dragon Fly, others Adder Bolt, Balance Fly, Perla, Libellula or Libella. I shall prefer the last, as conveying an idea well known to English adepts. The caterpillars of them all live in ponds and stagnant waters (that are undisturbed by cattle) during the greatest part of their lives, and make their appearance under three general forms. The first is shewn by Fig. 1. 1.; the second by Fig. 2.; and the third by Fig. 3. See Plate 47. As these are the shapes in which they all appear, it will not be improper to mention each particularly.

"The two caterpillars at Fig. 1. 1. Plate 47, belong only to or produce those that sit at rest, with their wings erect, (see Plate 48. Fig. 2.), and differ from both the others not only in size but in the roundness and slenderness of their bodies; at the extremity whereof they are furnished with three tails, each of which upon examination being found to be a kind of feather, and is an appendage that neither of the others have. Their behaviour also in the water is different from the others, being enabled to twist and bend their bodies in a more circular manner. [Subfamily Agrionides.]

"The second sort of caterpillars, at Plate 47. Fig. 2. are much shorter and thicker in their bodies than either of the others, producing those Libellas with flat bodies, as Plate 47. Fig. 4. and 6. and Plate 48. Fig. 1. and 5. These are, of all others, the most disagreeable in their appearance; most of them having their bodies and legs very rough and shaggy, and of the exact colour of mud. Others appear of a dirty green, and very unpleasing hue, a colour that in general reigns among them all; for none can boast of any beautiful appearance while in this state, unless the different shapes here exhibited can be called so. Indeed the beauty and symmetry, so apparent in their complete states, make ample amends for the want of it in this; all of them in general being then very beautiful, discovering colours superior to art. [Subfamily, Libellulides. Genus, Libellula.]

"The caterpillars of the third sort (see Plate 47. Fig. 3.) are very different from the preceding, being the size of the figure, with the abdomen flat at bottom and rounding at top, longer and slenderer than those at Fig. 2. but not so much as those at Fig. 1. 1. These produce those large Libellas with long slender bodies, who sit at rest with their wings expanded, as Plate 47. Fig. 5. [Subfamily, Libellulides. Genus, Æshna.]

"Under these three forms are all the caterpillars of Libellas found, there being but little difference in the colours or marks of the respective tribes; the various sizes and shapes being the chief observable circumstances attending them. They are all furnished with six legs, and have each of them four little membranaceous substances issuing from the back, or upper part of the thorax, that are the follicles, or cases, wherein the wings are inclosed. When the young caterpillars issue from their confinement in the eggs, there is no appearance of these cases, nor till a considerable time after; but as they arrive to a maturer state they become more conspicuous, and, like the young leaves of trees that open and expand themselves on the arrival of the spring, their appearance increases, till having approached the period when they are to forsake their former habitations and become inhabitants of the air, these wing-cases have then arrived to their due size, and carry the appearance in which they are here seen. They are all of them, from the largest to the smallest, armed with a strong offensive weapon, which serves them, and is indeed the means they are endued with, for obtaining their food. This weapon being placed in the under part of the head, just beneath the mouth, I have displayed in Fig. 1. and 3. of Plate 47. where it appears just in the same manner as when they are endeavouring to catch their prey. In the largest figure at 1. and also in Fig. 2. it appears contracted and shut up, as when at rest. The strength and power that these animals discover in the use of this instrument is very singular and extraordinary. There are two joints to it, one about the middle, the other underneath the mouth, close to the throat; and in some (particularly all those of Fig. 2.) when it is closed or contracted, it appears fastened to the face of the creature, by fitting it so exactly as to form a perfect mask; covering the mouth, and reaching almost as high as the eyes. In others it is made to fit only the under part of the mouth, and when at rest is drawn up close underneath it. At the extremity of those that are extended may be observed two very strong and remarkable fangs; that, shutting over each other, form a pair of forceps, of such strength that few, if any of their captives, can escape if once inclosed therein. [This organ is the greatly developed lower lip of the larva, and is analogous in its structure to the same part in the imago.]

"The motion of these creatures in the water, particularly those of the largest size, is very slow; seldom exercising any swiftness or activity, unless they are disturbed and threatened with danger, in which case they can transport themselves to places of more security with the quickness or agility of a fish; but, in general, they appear to have so little inclination to move, that I have often seen them (I mean those that I have kept in glass bowls) remaining in their respective places above a week together, and could not discover the least motion in them, unless under the circumstance above mentioned, or when they had seen their prey and were advancing to seize it. The caterpillars of Fig. 1. 1. and 3. generally fix themselves to some little stick or straw, &c. that they find in the water, and there remain, as I said before, without stirring. Those of Fig. 2. are more frequently seen in motion among the thickest part of the roots and plants that grow there, routing and searching for those small animals inhabiting that part, which are their proper food. This aversion to motion, so apparent in those of No. 1. and 3., appears to me to be the effect of an extraordinary cunning and sagacity; and may be considered as the principal means by which they obtain their prey: for while they continue thus motionless in the water, the small animals, who constitute their proper food, approach them with less fear than they would otherwise do, not suspecting their grand enemy lies upon the watch to seize them the moment they come within his reach; but no sooner has their insensibility of danger brought them within a small distance of those destructive weapons (mentioned before, being placed under their mouths) but that very instant they dart upon them with the utmost rapidity, suddenly throwing out their forceps, and seizing them with as much eagerness as a pike does the unwary gudgeon; they then bring their forceps up to their mouth with their prey in it, and feast on their captive prisoner. Nor is their voracious nature less astonishing; and the greediness with which the large ones seize other small animals would hardly gain belief among persons entirely ignorant of this study. I have seen one of them, in less than an hour's space, devour three insects, each of which was full two thirds as big as itself; but, in general, the small ones are the sacrifices made by the greater; wherein I must observe, that when they have got a caterpillar of the small Libellas in their forceps, such as those of Fig. 1. Plate 47., they leave no part uneaten, except the three tails, which they let fall to the bottom, as perhaps not having substance in them sufficient to afford them proper nourishment; for as their food consists altogether of animals less than themselves, they neither spare the caterpillars of the lesser LibellÆ, nor confine themselves to those belonging to other tribes. They will eagerly prey upon the different kinds of Cads, or caterpillars of the PhryganeÆ; great numbers of whom, at certain seasons, quit those husks or cases they make and swim about, with less fear and dread than in the early part of the spring. I have also seen the caterpillars of the Notanecta's or Boat-flies devoured by them, and not seldom the small blood-worms, as they are called. In short, there are but few of the lesser animals that live in the water, but when once they get within the reach of their instruments will certainly fall victims to these freshwater Leviathans.

"I could never observe that these caterpillars ever threw off any exuvia, or skin, in their progress from the egg to the complete animal, as most other insects do that live in the open air; neither could I ever perceive any difference between the caterpillars and chrysalis's of this genus in their outward forms^[31]: the same voracious behaviour in seizing and devouring their prey, reigning both in one and the other; but that they internally undergo some material alteration, when passing their respective states, is what I do not entertain the least doubt of; as the organs of respiration during the creature's life in the water, appear to me to be under a necessity of receiving a great alteration, when they are to perform the same office in so different a medium as the air; nor can I suppose this business to be done in so quick and sudden a manner, as the short space of time in which the creature would then be passing from the caterpillar state to the perfect one would permit, without having the intestines prepared, as it were, and fitted by some previous change. However, as this is conjecture only, I shall dwell no longer on this head, my present purpose being to point out and describe their general circumstances and behaviour.

"When the caterpillars of the respective species have arrived to their full growth, and nature informs them they are to quit their former element of water, for one wherein they are to appear invested with very different powers, they prepare for this extraordinary change; and, creeping up the sticks, straws, or plants they find for their purpose, whose tops grow out of the water, they entirely quit that element, and, stopping at about six or eight inches above its surface, there fix themselves, and continue some time, till their internal form, growing too big to be confined within the skin, that a few minutes afterwards will be entirely thrown off, on a sudden, that part of it that covers the thorax, splits or bursts on the upper side, and the creature, pushing out its head, next disengages its fore legs, which fastening to any substance within its reach, draws gently the remainder of its body and legs entirely out, just as a man draws his leg out of a boot, leaving its slough or skin sticking in its place, and in the exact form wherein it appeared itself but a few moments before. Having thus quitted its former covering, it waits for the wings to expand themselves, and grow to their proper size, being before confined within those small cases I mentioned were placed on its back. In about half an hour, if the weather is favourable, this extraordinary operation is completed; and the wings having arrived to their proper size, the creature generally makes an effort to try its strength, well knowing, that if it fails in attempting to fly without being endued with a sufficient degree of it, it must certainly fall in that water it lately quitted, and there perish; but having made several motions with its wings, and finding its power equal to its desire, it suddenly flies into the air, and there fills up a character, as different from the former as one element is from the other. At the time this change is accomplishing, the instrument or weapon for catching their prey, before mentioned, by an effect of nature, totally disappears, and not the least vestige of it then remains; the mouth, indeed, is furnished with jaws, and those of a very extraordinary form (dividing themselves both horizontally and perpendicularly), but no part of them appear extended beyond the rest, or have the least appearance of being furnished with an instrument like what they had in their former state.^[32]

"Hitherto I have considered these creatures only in their infant or incomplete states; wherein the faculties and powers they are endued with, are entirely different from those of their perfect and complete ones. In the former I have described them swimming and grovelling about in the water, preying upon the lesser kinds of insects, being incapable of subsisting for any length of time out of that element; in the latter we must view them capable of flying in the open air, and conveying themselves from place to place. If they are then confined to the limits of a small pond, they are now capable of roving from tree to tree, and from field to field, darting and skimming along with all the rapidity and seeming joy, that a being sensible of, and exulting in its own powers, can be supposed to do; in short, we must now view them in shapes so distinct and different from their former ones, that they hardly seem to bear any relation to each other, except in their nature and appetites; for although they appear in a far more elegant dress than when in their caterpillar states, yet these are just the same, the same voracious inclinations subsisting now as formerly; hunting after, and preying upon, the lesser genera, with the same eagerness and desire as they did when inhabitants of the water. Incredible numbers of small moths, bees, flies with four and two wings, are the daily sacrifices offered to the insatiable appetites of these hungry gluttons; and where they devoured one insect in the water they now destroy a hundred, if the mildness of the season will permit them to range about in quest of them. In rainy weather they seldom or ever move, nor when the wind is very strong and boisterous. Indeed, it is not to be wondered at. The small insects, who are their proper food, being by the same reasons prevented from being abroad, consequently are an impediment to those motives, that so strongly induce the Libellas to fly about. During such inclement times they generally shelter themselves from the wind, &c. being suspended by their feet in a perpendicular position on some twig, that is remote and separate from any boughs, waiting in that manner, without motion, for better weather and sunshine.

"I am strongly inclined to believe, that the greater part, if not all the Libellas, are two years in passing from the egg to the complete animal. But as this is a circumstance I do not remember to have seen in any author, I shall not attempt to establish my opinion as an absolute truth. I shall mention my reasons for this belief, and leave it to every person either to confirm or confute it, as his observations shall hereafter give him an opportunity.

"In order to do this, it would be necessary I should mention the times when each species first makes its appearance here in England. But as this would not only take up too much of the reader's time, (there being at least twenty-two of them) but it would likewise be impossible to be understood by any, but the experienced adept, unless I gave figures of them all; I shall therefore content myself with observing, that the Libella figured in Plate 47. Fig. 5. though found in America, about New York, &c. is nearly the same with our English one, differing but a very little from it, and which I have inserted chiefly as an instance to illustrate this subject. Ours is the last species but one, that comes forth in the summer, breeding only once a year, appearing about the 2nd of August. Therefore, to elucidate this point, suppose we allow a fortnight or three weeks from that time for all the Libellas of this species to make their appearance in, that nature intended should be bred that year; but in order to set this matter in the strongest light, I shall allow a month to that purpose. If, therefore, the Libellas were only one year in passing from the egg to the perfect state, we might justly conclude, that after the 2nd of September, (a month from the time of their first appearing) all of this species would have arrived to their complete states; and that none of their caterpillars could be found in the waters after that time, by reason they had all quitted that element, and were become flying insects. This, I say, is the conclusion we might fairly, and without presuming on the matter, make. But this is very far from being the case. For let any one examine stagnant waters at any time during the months of August, September, or October, and from thence in any part of the following winter, and he will find these very caterpillars at any of those times: and this, not in any one particular year, but they will be found also in any one whatever, fully fed, and of the largest size. Nor are the caterpillars of this species the only ones to be found fully fed. Those of N^o. 2. belonging to the flat-bodied Libella, will also be found very plentifully, many of them being of the first magnitude, together with numbers of the same species, very young according to the time of year when sought for; and appearing to have been hatched from those eggs that were laid by parent insects in the spring; for such I must conclude them to be, how else can we account for their smallness, at the same time that we may find others of the largest size? We must not suppose there can be this difference of size in the same species, owing to some eggs having been laid three weeks or a month sooner than others; that, being so short a space of time as not to allow it possible for one of those caterpillars to attain its full size, (and all the species of flat-bodied Libellas appear within a month of each other.) Nor can we be so deceived as to mistake a species of the long-bodied caterpillars, for one of the short-bodied; the difference being extremely apparent at the first glance.

"These reasons appear to me so convincing, I should have thought myself inexcuseable to have passed them over in silence, when I was giving the history of these animals. I shall therefore think myself happy to have this circumstance corroborated by future experience, or rectified and cleared up, if found to be an error. I shall only say, I have dwelt the longer on it, as it is an observation I never heard of before. I have likewise singled out the largest Libella, and the flat-bodied ones for its illustration, as being more conspicuous by their size, and easier to be observed than those of the smaller sorts.

"The two principles of hunger and lust, so apparent through the animal kingdom, are in no class or tribe more manifest and visible than in these insects. The former I have described and explained through their different states; it remains for me to shew the manner in which they obey the calls of the latter. And herein I must observe, that the different manner in which the act of copulation is performed, depends on the difference of the respective kinds; the organs of generation being placed in different parts of the body, according to the distinct species. All the flat-bodied ones have those parts placed in common with most other insects, at the extremity of the tail. In all the slender-bodied ones, the organ of the male is placed next the breast, close to the part where the thorax and abdomen unite; while the same organ in the female lies in the very extremity of the tail, and the singular manner of these creatures coupling is a circumstance worthy of observation.

"As soon as they have arrived to their perfect state, the males seek out their mates, in order to propagate their species; for this purpose they frequent ponds and standing waters, places where the females generally harbour, and when the male in the course of his flight comes within a certain distance of her, if it be one of that species whose sexual parts in both sexes are placed in the tail, he immediately flies to her, and fixing himself by his feet to the hinder part of her abdomen, bends his body round her tail, and performs the business of generation, both flying about all the time this act is performing; the whole transaction not exceeding the space of half a minute. Within a few hours after, the female, thus impregnated, begins to lay her eggs in the following manner. She singles out a leaf, grass, or some such matter, that is floating just below the surface of the water, in some pond, and, hovering in the air about a foot above this spot, on a sudden she descends, and dips the extremity of her tail in the water, at which instant she discharges an egg, that at the moment of its emission is inveloped in a glutinous liquid, sufficiently tenacious to enable it to adhere firmly on the floating substance above-mentioned without sinking. In this manner she continues depositing them till she has discharged the proper quantity, hovering in the air all the time, and emitting them as fast as the pendulum of a clock performs its vibrations; placing them close to one another in no regular or exact order. Whether she discharges at one time all her quantity of eggs, or only those that were fecundated and ready for emission, waiting to have the remaining eggs within her again fecundated by the male, or whether the first act of copulation sufficiently impregnates the whole quantity which she discharges at different times, as nature ripens them, is a circumstance I cannot determine. However this may be, it is certain she does not discharge them all at once; but comes again to the same place, when those within her are ready for emission, and there lays them in the same manner as at first.

"In this manner all the flat-bodied Libellas copulate and lay their eggs; the others, which are formed with slender bodies, behave very differently in every circumstance; for in each of those species, when the male has singled out its mate, he flies to her, and by means of two little bony substances placed at the end of his tail, issuing on each side, and composing a kind of forceps, he fixes himself to the forepart of her neck, close behind the head, the female discovering no sign of fear while he is performing this action; having fixed himself in this position, he remains there several days, sometimes appearing with his body quite erect, at other times bending himself, and settling with his legs on the same substance she may happen to alight on, without ever quitting his hold; but flies through the air, thus united, wherever the fancy or inclination of the female disposes her to go. This behaviour we must consider as a prelude to copulation, for that is not performed till a considerable time after they are thus united; and therefore I look on it as a wooing, or act of courtship in the male. But having remained a sufficient time in this manner, that is, till the female is disposed to receive him, she bends her tail round to that part where I described the organ of generation to be placed in the male, and, being still held fast by the neck, in that attitude they perform the mandate of nature. This action being over, that in the smaller kinds takes up a considerable space of time (for I have known them in this posture above eighteen hours) the female soon after begins to lay her eggs. She flies to some rush, reed, or other plant growing in the water, and settling close to its edge dips the end of her tail a little below the surface, and fixes her eggs to the rush or substance she is settled on; which, by means of the glutinous matter all eggs of this kind are surrounded with, adheres sufficiently fast, and there remains till the heat of the sun has brought the young animal into life; which immediately on quitting its confinement sinks to the bottom, or repairs to the place where nature directs it to seek out its food.

"In this manner all the slender-bodied tribe behave, differing only in some particular circumstances; as, for instance, the largest Libellas, as that at Fig. 5. Pl. 47. are not near so long in copulating or wooing as the small ones; for by the former this act is performed in a very short space, and while they are flying about in the air. Others, of a smaller size, are less quick in this performance; and as we descend to the smallest species, we shall find they take by much the longest time; observing, by the way, that all these slender-bodied ones lay their eggs in the same manner, that is, by fixing them to some substance to which they adhere, till they are ripened into life. My experience well informing me they never scatter them in any loose careless manner as some insects do, but are placed in such proper and apt situations as to receive the influence of the sun to bring them to maturity.

"If we attentively consider these creatures, either in their caterpillar or complete states, we cannot help concluding them to be a rank of beings of greater benefit and advantage to mankind than they appear to be at first view; for, not to mention their being annual 'ministers of nature,' they are appointed by the great Governor of the universe as grand instruments for assisting to preserve that equilibrium so apparently reigning through the insect world, and which all who have made any progress in the study of natural history unanimously confess. Hence the voracious disposition of the Libellas is wisely made to answer a most necessary and beneficial purpose; and the great numbers of small insects which are daily sacrificed to their insatiable appetites, both in their caterpillar as well as complete states, is as strong an instance as any I know of the necessity and propriety of the existence of these animals. The general principle reigning through the whole animal kingdom, of the stronger preying upon the weak and defenceless, can hardly be explained to the purpose of being useful to mankind, and agreeable to the laws of nature, in any one instance more than is evidently to be observed in the subjects I have been describing. The least reflection will confirm this; for if the food of the Libellas when in their complete forms had consisted of the leaves of plants, like the locust genus, and not of those small insects they now prey on; or had it, like the beetle tribe, consisted of the superfluous parts of nature, as the putrid carcases of dead animals, rotten wood, &c. how great a chasm would there have been in the universal chain? how evident and conspicuous would it have appeared? and how could the vast number of small insects, increasing every day during the summer, be restrained and lessened? what genus of the transparent-winged class could possibly have performed this business singly? or could all the genera of flies, and even birds that we know of, have accomplished this end? could all the DipterÆ, or any other kinds that prey on the lesser genera, have prevented such an increase of them as to become in a little time a plague too great to be borne? No. The Almighty Creator has most wisely constituted this genus for executing His commands in the manner I have described; and for this reason they must be considered as beings of greater consequence than the inconsiderate part of mankind allow them to be.

"Nor is this the only advantage arising from their existence. The still waters, where these creatures are inhabitants during their infant state, are in some degree by their assistance preserved sweet and good, that otherwise might corrupt and putrify, for the motion the waters receive by these insects is not trifling; the respiration they perform in that element being observable by a close attention, which, together with that and the motion of thousands of other insects, does in some measure contribute to keep it sweet and wholesome."