These beetles, however, in point of industry must yield the palm to one (Necrophorus Vespillo) whose singular history was first detailed by M. Gleditsch inthe Acts of the Berlin Societyfor 1752. He begins by informing us that he had often remarked that dead moles when laid upon the ground, especially if upon loose earth, were almost sure to disappear in the course of two or three days, often of twelve hours. To ascertain the cause, he placed a mole upon one of the beds in his garden. It had vanished by the third morning; and on digging where it had been laid, he found it buried to the depth of three inches, and under it four beetles which seemed to have been the agents in this singular inhumation. Not perceiving any thing particular in the mole, he buried it again; and on examining it at the end of six days he found it swarming with maggots apparently the issue of the beetles, which M. Gleditsch now naturally concluded had buried the carcase for the food of their future young. To determine these points more clearly, he put four of these insects into a glass vessel half filled with earth and properly secured, and upon the surface of the earth two frogs. In less than twelve hours one of the frogs wasinterred by two of the beetles: the other two ran about the whole day as if busied in measuring the dimensions of the remaining corpse, which on the third day was also found buried. He then introduced a dead linnet. A pair of the beetles were soon engaged upon the bird. They began their operations by pushing out the earth from under the body so as to form a cavity for its reception; and it was curious to see the efforts which the beetles made by dragging at the feathers of the bird from below to pull it into its grave. The male having driven the female away continued the work alone for five hours. He lifted up the bird, changed its place, turned it and arranged it in the grave, and from time to time came out of the hole, mounted upon it and trod it under foot, and then retired below and pulled it down. At length, apparently wearied with this uninterrupted labour, it came forth and leaned its head upon the earth beside the bird without the smallest motion as if to rest itself, for a full hour, when it again crept under the earth. The next day in the morning the bird was an inch and a half under ground, and the trench remained open the whole day, the corpse seeming as if laid out upon a bier, surrounded with a rampart of mould. In the evening it had sunk half an inch lower, and in another day the work was completed and the bird covered.—M. Gleditsch continued to add other small dead animals, which were all sooner or later buried; and the result of his experiment was, that in fifty days four beetles had interred in the very small space of earth allotted to them, twelve carcases: viz. four frogs, three small birds, two fishes, one mole, and two grasshoppers, besides the entrails of a fish, and two morsels of the lungs of an ox. In another experiment a single beetle buried a mole fortytimes its own bulk and weight in two days[669]. It is plain that all this labour is incurred for the sake of placing in security the future young of these industrious insects along with a necessary provision of food. One mole would have sufficed a long time for the repast of the beetles themselves, and they could have more conveniently fed upon it above ground than below. But if they had left thus exposed the carcase in which their eggs were deposited, both would have been exposed to the imminent risk of being destroyed at a mouthful by the first fox or kite that chanced to espy them.
At the first view I dare say you feel almost inclined to pity the little animals doomed to exertions apparently so disproportioned to their size. You are ready to exclaim that the pains of so short an existence, engrossed with such arduous and incessant toil, must far outweigh the pleasures. Yet the inference would be altogether erroneous. What strikes us as wearisome toil, is to the little agents delightful occupation. The kind Author of their being has associated the performance of an essential duty with feelings evidently of the most pleasurable description; and, like the affectionate father whose love for his children sweetens the most painful labours, these little insects are never more happy than when thus actively engaged. "A bee," as Dr. Paley has well observed, "amongst the flowers in spring, (when it is occupied without intermission in collecting farina for its young or honey for its associates,) is one of the cheerfullest objects that can be looked upon. Its life appears to be all enjoyment: so busy and so pleased[670]."
Of the sources of exquisite gratification which everyrural walk will open to you, while witnessing in the animals themselves those marks of affection for their unseen progeny of which I have endeavoured to give you a slight sketch, it will be none of the least fertile to examine the various and appropriate instruments with which insects have been furnished for the effective execution of their labours. The young of the saw-fly tribe (Serrifera[671]) are destined to feed upon the leaves of rose-trees and various other plants. Upon the branches of these the parent fly deposits her eggs in cells symmetrically arranged; and the instrument with which she forms them is a saw, somewhat like ours but far more ingenious and perfect, being toothed on each side, or rather consisting of two distinct saws, with their backs (the teeth or serratures of which are themselves often serrated, and the exterior flat sides scored and toothed), which play alternately; and, while their vertical effect is that of a saw, act laterally as a rasp. When by this alternate motion the incision, or cell, is made, the two saws, receding from each other, conduct the egg between them into it[672]. TheCicada, so celebrated by the poets of antiquity, which lays its eggs in dry wood, requires a stronger instrument of a different construction. Accordingly it is provided with an excellent double auger, the sides of which play alternately and parallel to each other, and bore a hole of the requisite depth in very hard substances without ever being displaced.
The construction of the sting or ovipositor with whichthe different species of Ichneumon are provided, is not less nicely adapted to its various purposes. In those which lay their eggs in the bodies of caterpillars that feed exposed on the leaves of plants it is short, often in very large species not the eighth of an inch long: having free access to their victims, a longer sting would have been useless. But a considerable number oviposit in larvæ which lie concealed where so short an instrument could not possibly approach them. In these, therefore, the sting is proportionably elongated, so much so that in some small species it is three or four times the length of the body. Thus inPimpla Manifestator, whose economy has been so pleasingly illustrated by Mr. Marsham[673], and which attacks the larva of a wild bee (Chelostoma[674]maxillosa) lying at the bottom of deep holes in old wood, the sting is nearly two inches long[675]: and it is not much shorter in the more minuteI. StrobilellæL., which lays its eggs in larvæ concealed in the interior of fir cones, which without such an apparatus it would never be able to reach.
The tail of the females of many moths whose eggs require to be protected from too severe a cold and too strong a light, is furnished, evidently for application to this very purpose, with a thick tuft of hair. But how shall the moth detach this non-conducting material and arrange it upon her eggs? Her ovipositor is provided at the end with an instrument resembling a pair of pincers, which for this purpose are as good as hands. With these, having previously deposited her eggs upon a leaf she pulls off her tuft of hairs, with which she so closely envelopsthem as effectually to preserve them of the required temperature: and having performed this last duty to her progeny she expires.
The ovipositor of the capricorn beetles, an infinite host, is a flattened retractile tube, of a hard substance, by means of which it can introduce its eggs under the bark of timber, and so place them where its progeny will find their appropriate food[676]. The auger used by certain species of Œstrus, to enable them to penetrate the hides of oxen or deer and form a nidus for their eggs, has been before described[677].—But to enumerate all the varieties of these instruments would be endless.
The purpose which in the insects above mentioned is answered by their anal apparatus, is fulfilled in the numerous tribes of weevils by the long slender snout with which their head is provided. It is with this thatBalaninus Nucumpierces the shell of the nut, and the weevil (Calandra granaria) the skin of the grains of wheat, in which they respectively deposit their eggs, prudently introducing one only into each nut or grain, which is sufficient, but not more than sufficient, for the nourishment of the grub that will inhabit it.
II. Hitherto I have adverted to those insects only which perish before their young come into existence, and can therefore evince their affection for them in no other way than by placing the eggs whence they are to spring in secure situations stored with food; and these include by far the largest portion of the race. A very considerable number, however, extend their cares much further: they not only watch over their eggs after depositingthem, but attend upon their young, when excluded, with an affectionate assiduity equal to any thing exhibited amongst the larger animals, and in the highest degree interesting. Of this description are some solitary insects, as several species of the Linnean genus Sphex, earwigs, field-bugs, and spiders: and those insects which live in societies, namely, ants, bees, wasps, and termites: the most striking traits of whose history in these respects I shall endeavour to lay before you.
You have seen that the greater number of theSphecinaafter depositing their eggs in cells stored with a supply of food, take no further care of them. Some, however, adopt a different procedure. One of these, called by Bonnet theMason-wasp, but different from Reaumur's, not only incloses a living caterpillar along with its egg in the cell, which it carefully closes, but at the expiration of a few days, when the young grub has appeared and has consumed its provision, re-opens the nest, incloses a second caterpillar, and again shuts the mouth: and this operation it repeats until the young one has attained its full growth[678]. A similar mode, according to Rolander, is followed byAmmophila vulgarisas well as by the yellowish wasp of Pennsylvania, described by Bartram in thePhilosophical Transactions[679], and by another related toMellinus arvensis, observed by Duhamel[680]; both of which, however, instead of caterpillars, supply their larvæ with a periodical provision of living flies.
What a crowd of interesting reflections are these most singular facts calculated to excite! With what foresight must the parent insect be endowed, thus to be aware atwhat period her eggs will be hatched into grubs, and how long the provision she has laid up will suffice for their support! What an extent of judgement, thus in the midst of various other occupations to know the precise day when a repetition of her cares will be required! What an accuracy of memory, to recollect with such precision the entrance to her cell, which the most acute eye could not discover; and without compass or direction unerringly to fly to it, often from a great distance and after the most intricate and varied wanderings! If we refer the whole to instinct, and to instinct doubtless it must in the main if not wholly be referred, our admiration is not lessened. Instinct, when simple and directed to one object, is less astonishing; but such a complication of instincts, applied to actions so varied and dissimilar, is beyond our conception. We can but wonder and adore!
We are indebted to De Geer for the history of a field-bug (Pentatoma grisea), a species found in this country, which shows marks of affection for her young such as I trust will lead you, notwithstanding any repugnant association that the name may call up, to search upon the birch tree, which it inhabits, for so interesting an insect. The family of this field-bug consists of thirty or forty young ones, which she conducts as a hen does her chickens. She never leaves them; and as soon as she begins to move, all the little ones closely follow, and whenever she stops assemble in a cluster round her. De Geer having had occasion to cut a branch of birch peopled with one of those families, the mother showed every symptom of excessive uneasiness. In other circumstances such an alarm would have caused her immediate flight;but now she never stirred from her young, but kept beating her wings incessantly with a very rapid motion, evidently for the purpose of protecting them from the apprehended danger[681].—As far as our knowledge of the economy of this tribe of insects extends, there is no other species that manifests a similar attachment to its progeny; but such may probably be discovered by future observers.
It is De Geer also that we have to thank for a series of interesting observations on the maternal affection exhibited by the common earwig. This curious insect so unjustly traduced by a vulgar prejudice,—as if the Creator had willed that the insect world should combine within itself examples of all that is most remarkable in every other department of nature,—still more nearly approaches the habits of the hen in her care of her family. She absolutely sits upon her eggs as if to hatch them—a fact which Frisch appears first to have noticed—and guards them with the greatest care. De Geer, having found an earwig thus occupied, removed her into a box where was some earth, and scattered the eggs in all directions. She soon, however, collected them one by one with her jaws into a heap, and assiduously sat upon them as before. The young ones, which resemble the parent except in wanting elytra and wings, and, strange to say, are as soon as born larger than the eggs which contained them, immediately upon being hatched creep like a brood of chickens under the belly of the mother, who very quietly suffers them to push between her feet, and will often, as De Geer found, sit over them in this posture for some hours[682]. This remarkable fact I have myself witnessed, having found an earwig under a stone which I accidentallyturned over, sitting upon a cluster of young ones just as this celebrated naturalist has described.
We are so accustomed to associate the ideas of cruelty and ferocity with the name of spider, that to attribute parental affection to any of the tribe seems at first view almost preposterous. Who indeed could suspect that animals which greedily devour their own species whenever they have opportunity, should be susceptible of the finer feelings? Yet such is the fact. There is a spider common under clods of earth (Lycosa saccata) which may at once be distinguished by a white globular silken bag about the size of a pea, in which she has deposited her eggs, attached to the extremity of her body. Never miser clung to his treasure with more tenacious solicitude than this spider to her bag. Though apparently a considerable incumbrance, she carries it with her every where. If you deprive her of it, she makes the most strenuous efforts for its recovery; and no personal danger can force her to quit the precious load. Are her efforts ineffectual? A stupefying melancholy seems to seize her, and when deprived of this first object of her cares, existence itself appears to have lost its charms. If she succeeds in regaining her bag, or you restore it to her, her actions demonstrate the excess of her joy. She eagerly seizes it, and with the utmost agility runs off with it to a place of security. Bonnet put this wonderful attachment to an affecting and decisive test. He threw a spider with her bag into the cavern of a large ant-lion, a ferocious insect which conceals itself at the bottom of a conical hole constructed in the sand for the purpose of catching any unfortunate victim that may chance to fall in. The spider endeavoured to run away, but was notsufficiently active to prevent the ant-lion from seizing her bag of eggs, which it attempted to pull under the sand. She made the most violent efforts to defeat the aim of her invisible foe, and on her part struggled with all her might. The gluten, however, which fastened her bag, at length gave way, and it separated: but the spider instantly regained it with her jaws, and redoubled her efforts to rescue the prize from her opponent. It was in vain: the ant-lion was the stronger of the two, and in spite of all her struggles dragged the object of contestation under the sand. The unfortunate mother might have preserved her own life from the enemy: she had but to relinquish the bag, and escape out of the pit. But, wonderful example of maternal affection! she preferred allowing herself to be buried alive along with the treasure dearer to her than her existence; and it was only by force that Bonnet at length withdrew her from the unequal conflict. But the bag of eggs remained with the assassin: and though he pushed her repeatedly with a twig of wood, she still persisted in continuing on the spot. Life seemed to have become a burthen to her, and all her pleasures to have been buried in the grave which contained the germe of her progeny[683]! The attachment of this affectionate mother is not confined to her eggs. After the young spiders are hatched, they make their way out of the bag by an orifice, which she is careful to open for them, and without which they could never escape[684]; and then, like the young of the Surinam toad (Rana pipa), they attach themselves in clusters upon her back, belly, head, and even legs; and in this situation, where they present a very singular appearance, she carriesthem about with her and feeds them until their first moult, when they are big enough to provide their own subsistence. I have more than once been gratified by a sight of this interesting spectacle; and when I nearly touched the mother, thus covered by hundreds of her progeny, it was most amusing to see them all leap from her back and run away in every direction.
A similar attachment to their eggs and young is manifested by many other species of the same tribe, particularly of the generaLycosaandDolomeda.Clubiona holosericeawas found by De Geer in her nest with fifty or sixty young ones, when manifesting nothing of her usual timidity, so obstinately did she persist in remaining with them, that to drive her away it was necessary to cut her whole nest in pieces[685].
I must now conduct you to a hasty survey of those insects which live together in societies and fabricate dwellings for the community, such asants,wasps,bees,humble-bees, andtermites, whose great object (sometimes combined indeed with the storing up of a stock of winter provisions for themselves) is the nutrition and education of their young. Of the proceedings of many of these insects we know comparatively nothing. There are, it is likely, some hundreds of distinct species of bees which live in societies, and form nests of a different and peculiar construction. The constitution of these societies is probably as various as the exterior forms of their nests, and their habits possibly curious in the highest degree; yet our knowledge is almost confined to the economy of the hive-bee and of some species of humble-bees. Thesame may be said of wasps, ants, and termites, of which, though there is a vast variety of different kinds, we are acquainted with the history of but a very few. You will not therefore expect more than a sketch of the most interesting traits of affection for their young, manifested by the common species of each genus.
One circumstance must be premised with regard to the education of the young of most of those insects which live in society, truly extraordinary, and without parallel in any other department of nature: namely, that this office, except under particular circumstances, is not undertaken by the female which has given birth to them, but by the workers, or neuters as they are sometimes called, which, though bound to the offspring of the common mother of the society by no other than fraternal ties, exhibit towards them all the marks of the most ardent parental affection, building habitations for their use, feeding them and tending them with incessant solicitude, and willingly sacrificing their lives in defence of the precious charge. Thus sterility itself is made an instrument of the preservation and multiplication of species; and females too fruitful to educate all their young, are indulged by Providence with a privilege without which nine tenths of their progeny must perish.
The most determined despiser of insects and their concerns—he who never deigned to open his eyes to any other part of their economy—must yet have observed, even in spite of himself, the remarkable attachment which the inhabitants of a disturbed nest ofantsmanifest towards certain small white oblong bodies with which it is usually stored. He must have perceived that the ants are much less intently occupied with providing for their ownsafety, than in carrying off these little bodies to a place of security. To effect this purpose the whole community is in motion, and no danger can divert them from attempting its accomplishment. An observer having cut an ant in two, the poor mutilated animal did not relax in its affectionate exertions. With that half of the body to which the head remained attached, it contrived previously to expiring to carry off ten of these white masses into the interior of the nest! You will readily divine that these attractive objects are the young of the ants in one of the first or imperfect states. They are in fact not the eggs, as they are vulgarly called, but the pupæ, which the working ants tend with the most patient assiduity. But I must give you a more detailed account of their operations, beginning with the actual eggs.
These, which are so small as to be scarcely visible to the naked eye, as soon as deposited by the queen ant, who drops them at random in her progress through the nest, are taken charge of by the workers, who immediately seize them and carry them in their mouths, in small parcels, incessantly turning them backwards and forwards with their tongue for the purpose of moistening them, without which they would come to nothing. They then lay them in heaps, which they place in separate apartments[686], and constantly tend until hatched into larvæ; frequently in the course of the day removing them from one quarter of the nest to another, as they require a warmer or cooler, a moister or drier atmosphere; and at intervals brooding over them as if to impart a genial warmth[687]. Experiments have been made to ascertain whether these assiduous nurses could distinguish their eggs if intermixed withparticles of salt and sugar, which to an ordinary observer they very much resemble; but the result was constantly in favour of the sagacity of the ants. They invariably selected the eggs from whatever materials they were mixed with, and re-arranged them as before[688].
New and more severe labours succeed the birth of the young grubs which are disclosed from the eggs after a few days. The working ants are now almost without remission engaged in supplying their wants and forwarding their growth. Every evening an hour before sunset they regularly remove the whole brood, as well as the eggs and pupæ, which in an old nest all require attention at the same time, to cells situated lower down in the earth, where they will be safe from the cold; and in the morning they as constantly remove them again towards the surface of the nest. If, however, there is a prospect of cold or wet weather, the provident ants forbear on that day transporting their young from the inner cells, aware that their tender frames are unable to withstand an inclement sky. What is particularly worthy of notice in this herculean task, the ants constantly regulate their proceedings by the sun, removing their young according to the earlier or later rising and setting of that luminary. As soon as his first rays begin to shine on the exterior of the nest, the ants that are at the top go below in great haste to rouse their companions, whom they strike with their antennæ, or, when they do not seem to comprehend them, drag with their jaws to the summit till a swarm of busy labourers fill every passage. These take up the larvæ and pupæ, which they hastily transport to the upper part of their habitation, where they leave them a quarter ofan hour, and then carry them into apartments where they are sheltered from the sun's direct rays[689].
Severe as this constant and unremitted daily labour seems, it is but a small part of what the affection of the working ants leads them readily to undertake. Thefeedingof the young brood, which rests solely upon them, is a more serious charge. The nest is constantly stored with larvæ the year round, during all which time, except in winter when the whole society is torpid, they require feeding several times a day with a viscid half-digested fluid that the workers disgorge into their mouths, which when hungry they stretch out to meet those of their nurses. Add to which, that in an old nest there are generally two distinct broods of different ages requiring separate attention; and that the observations of Huber make it probable that at one period they require a more substantial food than at another. It is true that the youngest brood at first want but little nutriment: but still, when we consider that they must not be neglected, that the older brood demand incessant supplies, and in a well stocked nest amount to 7 or 8000; and that the task of satisfying all these cravings, as well as providing for their own subsistence, falls to the lot of the working ants, we are almost ready to regard the burthen as greater than can be borne by such minute agents; and we shall not wonder at the incessant activity with which we see them foraging on every side.
Their labour does not end here. It is necessary that the larvæ should be kept extremely clean; and for this purpose the ants are perpetually passing their tongue and mandibles over their body, rendering them by this means perfectly white[690]. After the young grubs have attainedtheir full growth, they surround themselves with a silken cocoon and become pupæ, which, food excepted, require as much attention as in the larva state. Every morning they are transported from the bottom of the nest to the surface, and every evening returned to their former quarters. And if, as is often the case, the nest be thrown into ruins by the unlucky foot of a passing animal, in addition to all these daily and hourly avocations, is superadded the immediate necessity of collecting the pupæ from the earth with which they have been mixed, and of restoring the nest to its pristine state[691].
Nothing can be more curious than the view of the interior of a fully peopled ants' nest in summer. In one part are stored the eggs; in another the pupæ are heaped up by hundreds in spacious apartments; and in a third we see the larvæ surrounded by the workers, some of which feed them, while others keep guard, standing erect upon their hind legs with their abdomen elevated in the position for ejaculating their acid, than which, gunpowder would not be more formidable to the majority of their foes. Some again are occupied in cleaning the alleys from obstructions of various kinds; and others rest in perfect repose recruiting their strength for new labours.
Contrary to what is observed amongst other insects, even the extrication of the young ants from the silkencocoon which incloses them is imposed upon the workers, who are taught by some sensation to us incomprehensible, that the perfect insect is now ready to burst from the shroud, but too weak to effect its purpose unaided. When the workers discover that this period has arrived, a great bustle prevails in their apartment. Three or four mount upon one cocoon, and with their mandibles begin to open it where the head lies. First they pull off a few threads to render the place thinner; they then make several small openings, and with great patience cut the threads which separate them one by one, till an orifice is formed sufficiently large for extracting the prisoner; which operation they perform with the utmost gentleness. The ant is still enveloped in its pellicle; this the workers also pull off, carefully disengaging every member from its case, and nicely expanding the wings of such as are furnished with them. After thus liberating and afterwards feeding the new-born insects, they still for several days watch and follow them every where, teaching them to unravel the paths and winding labyrinths of the common habitation[692]; and when the males and females at length take flight, these affectionate stepmothers accompany them, mounting with them to the summit of the highest herbs, showing the most tender solicitude for them, (some even endeavour to retain them,) feeding them for the last time, caressing them; and at length, when they rise into the air and disappear, seeming to linger for some seconds over the footsteps of these favoured beings, of whom they have taken such exemplary care, and whom they will never behold again[693].
In the above account, exclusive of the bare fact of theirlaying the eggs, no mention is made of the female ants, the real parents of the republic. You are not from this to suppose that they never feel the influence of this divine principle of love for their offspring. When, indeed, a colony is established and peopled, they have enough to do to furnish it with eggs to produce its necessary supply of future females, males and workers; which, according to Gould, are laid at three different seasons[694]. This is the ordinary duty assigned to them by Providence. Yet at the first formation of a nest, the female acts the kind part, and performs all the maternal offices which I have just described as peculiar to the workers; and it is only when these become sufficiently numerous to relieve her, that she resigns this charge and devotes herself exclusively to oviposition[695].
There is one circumstance occurring at this period of their history, which affords a very affecting example of the self-denial and self-devotion of these admirable creatures. If you have paid any attention to what is going forward in an ant-hill, you will have observed some larger than the rest, which at first sight appear, as well as the workers, to have no wings, but which upon a closer examination exhibit a small portion of their base, or the sockets in which they were inserted. These are females that have cast their wings, not accidentally but by avoluntaryact. When an ant of this sex first emerges from the pupa, she is adorned with two pair of wings, the upper or outer pair being larger than her body. With these, when a virgin, she is enabled to traverse the fields of ether, surrounded by myriads of the other sex, who are candidates for her favour. But when once connubialrites are celebrated the unhappy husband dies, and the widowed bride seeks only how she may provide for their mutual offspring. Panting no more to join the choir of aërial dancers, her only thought is to construct a subterranean abode in which she may deposit and attend to her eggs, and cherish her embryo young, till, having passed through their various changes, they arrive at their perfect state, and she can devolve upon them a portion of her maternal cares. Her ample wings, which before were her chief ornament and the instruments of her pleasure, are now an incumbrance which incommode her in the fulfilment of the great duty uppermost in her mind; she therefore, without a moment's hesitation, plucks them from her shoulders. Might we not then address females who have families, in words like those of Solomon, "Go to the ant, yemothers, consider her ways and be wise"?
M. P. Huber was more than once witness to this proceeding. He saw one female stretch her wings with a strong effort so as to bring them before her head—she then crossed them in all directions—next she reversed them alternately on each side—at last, in consequence of some violent contortions, the four wings fell at the same moment in his presence. Another, in addition to these motions, used her legs to assist in the work[696].
Thus, from the very moment of the extrusion of the egg to the maturity of the perfect insect, are the ants unremittingly occupied in the care of the young of thesociety, and that with an ardour of affectionate attachment to which, when its intensity and duration are taken into the account, we may fairly say there is nothing parallel in the whole animal world[697]. Amongst birds and quadrupeds we have instances of affection as strong perhaps while it lasts, but how much shorter the period during which it is exerted! In a month or two the young of the former require no further attention; and if in a state of nature some of the latter give suck to their offspring for a longer period, it is on their parts without effort or labour; and in both cases the time given up to their young forms a very small part of the life of the animal. But the little insects in question not only spend a greater portion of time in the education of their progeny, but devote even the whole of their existence, from their birth to their death, to this one occupation!
The common hive-bee and the wasp in their attention to their young exhibit the same general features. Both build for their reception hexagonal cells, differing in size according to the future sex of the included grubs, which as soon as hatched they both feed and assiduously tend until their transformation into pupæ. There are peculiarities, however, in their modes of procedure, which require a distinct notice.
The economy of a nest ofwaspsdiffers from that of bees, in that the eggs are laid not by a single mother or queen, but by several; and that these mothers take the same care as the workers in feeding the young grubs: indeed those first hatched are fed entirely by the female which produced them, the solitary founder of the colony.The sole survivor probably of a last year's swarm of many thousands, this female, as soon as revived by the warmth of spring, proceeds to construct a few cells, and deposits in them the eggs of working wasps. The eggs are covered with a gluten, which fixes them so strongly against the sides of the cells, that it is not easy to separate them unbroken. These eggs seem to require care from the time they are laid, for the wasps many times in a day put their heads into the cells which contain them. When they are hatched, it is amusing to witness the activity with which the female runs from cell to cell, putting her head into those in which the grubs are very young, while those that are more advanced in age thrust their heads out of their cells, and by little movements seem to be asking for their food. As soon as they receive their portion, they draw them back and remain quiet. These she feeds until they become pupæ; and within twelve hours after being excluded in their perfect state, they eagerly set to work in constructing fresh cells, and in lightening the burthen of their parent by assisting her in feeding the grubs of other workers and females which are by this time born. In a few weeks the society will have received an accession of several hundred workers and many females, which without distinction apply themselves to provide food for the growing grubs, now become exceedingly numerous. With this object in view, as they collect little or no honey from flowers, they are constantly engaged in predatory expeditions. One party will attack a hive of bees, a grocer's sugar hogshead, or other saccharine repository; or, if these fail, the juice of a ripe peach or pear. You will be less indignant than formerly, at these audacious robbers now you know that self is little considered in their attacks, and thatyour ravaged fruit has supplied an exquisite banquet to the most tender grubs of the nest, into whose extended mouths the successful marauders, running with astonishing agility from one cell to another, disgorge successively a small portion of their booty in the same way that a bird supplies her young[698]. Another party is charged with providing more substantial aliment for the grubs of maturer growth. These wage war upon bees, flies, and even the meat of a butcher's stall, and joyfully return to the nest laden with the well-filled bodies of the former, or pieces of the latter as large as they can carry. This solid food they distribute in like manner to the larger grubs, which may be seen eagerly protruding their heads out of the cells to receive the welcome meal. As wasps lay up no store of food, these exertions are the task of every day during the summer, fresh broods of grubs constantly succeeding to those which have become pupæ or perfect insects; and in autumn, when the colony is augmented to 20 or 30,000, and the grubs in proportion, the scene of bustle which it presents may be readily conceived.
Though such is the love of wasps for their young, that if their nest be broken almost entirely in pieces they will not abandon it[699], yet when the cold weather approaches, a melancholy change ensues, followed by a cruel catastrophe, which at first you will be apt to regard as ill comporting with this affectionate character. As soon as the first sharp frost of October has been felt, the exterior of a wasp's nest becomes a perfect scene of horror. The old wasps drag out of the cells all the grubs and unrelentingly destroy them, strewing their dead carcasesaround the door of their now desolate habitation. "What monsters of cruelty!" I hear you exclaim, "what detestable barbarians!" But be not too hasty. When you have coolly considered the circumstances of the case, you will view this seemingly cruel sacrifice in a different light. The old wasps have no stock of provisions: the benumbing hand of Winter is about to incapacitate them from exertion; while the season itself affords no supply. What resource then is left? Their young must linger on a short period, suffering all the agonies of hunger, and at length expire. They have it in their power at least to shorten the term of this misery—to cut off its bitterest moments. A sudden death by their own hands is comparatively a merciful stroke. This is the only alternative; and thus, in fact, this apparent ferocity is the last effort of tender affection, active even to the end of life. I do not mean to say that this train of reasoning actually passes through the mind of the wasps. It is more correct to regard it as having actuated the benevolent Author of the instinct so singularly, and without doubt so wisely, excited. Were a nest of wasps to survive the winter, they would increase so rapidly, that not only would all the bees, flies, and other animals on which they prey, be extirpated, but man himself find them a grievous pest. It is necessary, therefore, that the great mass should annually perish; but that they may suffer as little as possible, the Creator, mindful of the happiness of the smallest of his creatures, has endowed a part of the society, at the destined time, with the wonderful instinct which, previously to their own death, makes them the executioners of the rest.
Wasps in the construction of their nests have solelyin view the accommodation of their young ones; and to these their cells are exclusively devoted.Bees, on the contrary, (I am speaking of the common hive-bee,) appropriate a considerable number of their cells to the reception of honey intended for the use of the society. Yet the education of the young brood is their chief object, and to this they constantly sacrifice all personal and selfish considerations. In a new swarm the first care is to build a series of cells to serve as cradles; and little or no honey is collected until an ample store ofbee-bread, as it is called, has been laid up for their food. This bee-bread is composed of the pollen of flowers, which the workers are incessantly employed in gathering, flying from flower to flower, brushing from the stamens their yellow treasure, and collecting it in the little baskets with which their hind legs are so admirably provided; then hastening to the hive, and having deposited their booty, returning for a new load. The provision thus furnished by one set of labourers is carefully stored up by another, until the eggs which the queen-bee has laid, and which adhering by a glutinous covering she places nearly upright in the bottom of the cell, are hatched. With this bee-bread after it has undergone a conversion into a sort of whitish jelly by being received into the bee's stomach, where it is probably mixed with honey[700]and regurgitated, the young brood immediately upon their exclusion, and until their change into nymphs, are diligently fed by other bees, which anxiously attend upon them and several times a day afford a fresh supply. Different bees areseen successively to introduce their heads into the cells containing them, and after remaining in that position some moments, during which they replace the expended provision, pass on to those in the neighbourhood. Others often immediately succeed, and in like manner put in their heads as if to see that the young ones have every thing necessary; which being ascertained by a glance, they immediately proceed, and stop only when they find a cell almost exhausted of food. That the office of these purveyors is no very simple affair will be admitted, when it is understood that the food of all the grubs is not the same, but that it varies according to their age, being insipid when they are young, and, when they have nearly attained maturity, more sugary and somewhat acid. The larvæ destined for queen-bees, too, require a food altogether different from that appropriated to those of drones and workers. It may be recognised by its sharp and pungent taste.
So accurately is the supply of food proportioned to the wants of the larvæ, that when they have attained their full growth and are ready to become nymphs, not an atom is left unconsumed. At this period, intuitively known to their assiduous foster-parents, they terminate their cares by sealing up each cell with a lid of wax, convex in those containing the larvæ of drones, and nearly flat in those containing the larvæ of workers, beneath which the inclosed tenants spin in security their cocoon.—In all these labours neither the queen nor the drones take the slightest share. They fall exclusively upon the workers, who, constantly called upon to tend fresh broods, as those brought to maturity are disposed of, devote nearly the whole of their existence to these maternal offices.
Humble-bees[701], which in respect of their general policy must, when compared with bees and wasps, be regarded as rude and untutored villagers, exhibit nevertheless marks of affection to their young quite as strong as their more polished neighbours. The females, like those of wasps, take a considerable share in their education. When one of them has with great labour constructed a commodious waxen cell, she next furnishes it with a store of pollen moistened with honey; and then having deposited six or seven eggs, carefully closes the orifice and minutest interstices with wax. But this is not the whole of her task. By a strange instinct, which, however, may be necessary to keep the population within due bounds, the workers, while she is occupied in laying her eggs, endeavour to seize them from her, and, if they succeed, greedily devour them. To prevent this violence, her utmost activity is scarcely adequate; and it is only after she has again and again beat off the murderous intruders and pursued them to the furthest verge of the nest, that she succeeds in her operation. When finished, she is still under the necessity of closely guarding the cell, which the gluttonous workers would otherwise tear open, and devour the eggs. This duty she performs for six or eight hours with the vigilance of an Argus, at the end of which time they lose their taste for this food, and will not touch it even when presented to them. Here the labours of the mother cease, and are succeeded by those of the workers. These know the precise hour when the grubs have consumed their stock of food, and fromthat time to their maturity regularly feed them with either honey or pollen, introduced in their proboscis through a small hole in the cover of the cell opened for the occasion and then carefully closed.
They are equally assiduous in another operation. As the grubs increase in size the cell which contained them becomes too small, and in their exertions to be more at ease they split its thin sides. To fill up these breaches as fast as they occur with a patch of wax, is the office of the workers, who are constantly on the watch to discover when their services are wanted; and thus the cells daily increase in size, in a way which to an observer ignorant of the process seems very extraordinary.
The last duty of these affectionate foster-parents is to assist the young bees in cutting open the cocoons which have inclosed them in the state ofpupæ. A previous labour however must not be omitted. The workers adopt similar measures with the hive-bee for maintaining the young pupæ concealed in these cocoons in a genial temperature. In cold weather and at night they get upon them and impart the necessary warmth by brooding over them in clusters. Connected with this part of their domestic economy, M. P. Huber, a worthy scion of a celebrated stock, and an inheritor of the science and merits of the great Huber as well as of his name, in his excellent paper on these insects in the sixth volume of the Linnean Transactions, from which most of these facts are drawn, relates a singularly curious anecdote.
In the course of his ingenious and numerous experiments, M. Huber put under a bell-glass about a dozen humble-bees without any store of wax, along with a comb of about ten silken cocoons so unequal in heightthat it was impossible the mass should stand firmly. Its unsteadiness disquieted the humble-bees extremely. Their affection for their young led them to mount upon the cocoons for the sake of imparting warmth to the inclosed little ones, but in attempting this the comb tottered so violently that the scheme was almost impracticable. To remedy this inconvenience, and to make the comb steady, they had recourse to a most ingenious expedient. Two or three bees got upon the comb, stretched themselves over its edge, and with their heads downwards fixed their fore feet on the table upon which it stood, whilst with their hind feet they kept it from falling. In this constrained and painful posture, fresh bees relieving their comrades when weary, did these affectionate little insects support the comb for nearly three days! At the end of this period they had prepared a sufficiency of wax with which they built pillars that kept it in a firm position: but by some accident afterwards these got displaced, when they had again recourse to their former manœuvre for supplying their place, and this operation they perseveringly continued until M. Huber, pitying their hard case, relieved them by fixing the object of their attention firmly on the table[702].
It is impossible not to be struck with the reflection that this most singular fact is inexplicable on the supposition that insects are impelled to their operations by a blind instinct alone. How could mere machines have thus provided for a case which in a state of nature has probably never occurred to ten nests of humble-bees since the creation? If in this instance these little animals were not guided by a process of reasoning, whatis the distinction between reason and instinct? How could the most profound architect have better adapted the means to the end—how more dexterouslyshoredup a tottering edifice, until his beams and his props were in readiness?
With respect to the operations of thetermitesin rearing their young I have not much to observe. All that is known is, that they build commodious cells for their reception, into which the eggs of the queen are conveyed by the workers as soon as laid, and where when hatched they are assiduously fed by them until they are able to provide for themselves.
In concluding this subject, it may not be superfluous to advert to an objection which is sometimes thrown out against regarding with any particular sympathy the affection of the lower animals to their young, on the ground that this feeling is in them the result of corporeal sensation only, and wholly different from that love which human parents feel for their offspring. It is true that the latter involves moral considerations which cannot have place in the brute creation; but it would puzzle such objectors to explain in what respect the affection which a mother feels for her new-born infant the moment it has seen the light, differs from that of an insect for its progeny. The affection of both is purely physical, and in each case springs from sensations interwoven by the Creator in the constitution of his creatures. If the parental love of the former is worthy of our tenderest sympathies, that of the latter cannot be undeserving of some portion of similar feeling.
I am, &c.
Insects like other animals draw theirfoodfrom the vegetable and animal kingdoms; but a very slight survey will suffice to show that they enjoy a range over far more extensive territories.
To begin with the vegetable kingdom.—Of this vast field the larger animals are confined to a comparatively small portion. Of the thousands of plants which clothe the face of the earth, when we have separated the grasses and a trifling number of herbs and shrubs, the rest are disgusting to them, if not absolute poisons. But how infinitely more plenteous is the feast to which Flora invites the insect tribes! From the gigantic banyan which covers acres with its shade, to the tiny fungus scarcely visible to the naked eye, the vegetable creation is one vast banquet at which her insect guests sit down. Perhaps not a single plant exists which does not afford a delicious food to some insect, not excluding even those most nauseous and poisonous to other animals—the acrid euphorbias, and the lurid henbane and nightshade. Nor is it a presumptuous supposition that a considerable proportion of these vegetables were created expressly for their entertainment and support. The common nettle is of little use either to mankind or the larger animals, but you will not doubt its importance to the class of insects,when told that at least thirty distinct species feed upon it. But this is not all. The larger herbivorous animals are confined to a foliaceous or farinaceous diet. They can subsist on no other part of a plant than its leaves and seeds, either in a recent or dried state, with the addition sometimes of the tender twigs or bark. Not so the insect race; to different tribes of which every part of a plant supplies appropriate food. Some attack its roots; others select the trunk and branches; a third class feed upon the leaves; a fourth with yet more delicate appetite prefer the flowers; and a fifth the fruit or seeds. Even still further selection takes place. Of those which feed upon the roots, stem, and branches, of vegetables, some larvæ eat only the bark (Sesia apiformis, &c.), others the alburnum (Semasia Wœberana), others the exuding resinous or other excretions (Scoparia Resinella), a third class the pith (Xanthia Ochraceago), and a fourth penetrate into the heart of the solid wood (Prionus,Lamia,Cerambyx, &c.). Of those which prefer the leaves, some taste nothing but the sap which fills their veins (Aphidesin all their states), others eat only the parenchyma, never touching the cuticle (subcutaneousTineæ,Gracillaria?) others only the lower surface of the leaf (manyTortrices), while a fourth description devour the whole substance of the leaf (mostLepidoptera). And of the flower-feeders, while some eat the very petals (Cucullia Verbasci,Xylina Linariæ, &c.), others in their perfect state select the pollen which swells the anthers (bees,Lepturæ, andMordellæ), and a still larger class of these the honey secreted in the nectaries (most of theLepidoptera,Hymenoptera, andDiptera).
Nor are insects confined to vegetables in their recentor unmanufactured state. A beam of oak when it has supported the roof of a castle five hundred years, is as much to the taste of some, (Anobia,) as the same tree was in its growing state to that of others; another class (Ptini) would sooner feast on the herbarium of Brunfelsius, than on the greenest herbs that grow; and a third (Tineæ,Termites), to whom