CHAPTER XVIII
Bees and wasps—A bee’s masonry—What happens to caterpillars—Living food—Variations in instinct—A wasp’s implement—Unreal distinctions—A cautious observer—Bees that make tunnels—A wonderful instinct—Leaf-cutting bees—Nests made of poppy-leaves—Born in the purple—Commercial philosophy—The appreciative white man—Economy of labour—Bees and rats—Busy shadows—A bee double.
THE consideration of ants naturally leads to that of bees, but of the life and doings of the hive-bee—made common now in a hundred practical treatises and bee-keeper’s manuals—it is not the design of this little book to treat. Wasps are less written about, but even here, in a work which can only deal with a very few insects out of a very great many, a choice may be permitted one, so I will merely observe, in regard to the common species, that in my opinion wasps are much less irascible than bees—in fact, quite good-natured compared to them—but at the same time, owing to their room-entering, table-pillaging propensities, much greater nuisances, so that they deserve stern treatment, but a more charitable estimate of their character. Hornets, again—which seldom offend in this way—appear to me to be very peaceable insects, as though, wielding a mighty weapon, they felt that they had no need to use it except on “a striking emergency.” Such a definition wouldapply to the running of a stage-coach, diligence, omnibus, waggon, etc.—in fact, any large vehicle—into their nest on the highway, in which case the consequences, one may well believe, would be appalling. Never having been in such a position myself, and being without trustworthy information on the subject, my powers of description are useless here, but there is a way of dealing with this emergency also. This reminds me, however, of an account which I have read somewhere or other of hornets having once stopped a Roman army. This may seem surprising nowadays, but we must remember that in classical times armies did not possess artillery. There is therefore nothing invidious in the opinion which I here express, that however much they may have stopped the Romans, they would never stop the Japanese.
In both ants and bees we find solitary and social species, so as in ants we have been considering the latter only, we will now reverse the process with bees. There are many interesting species of solitary bees, but it must be premised that the word “solitary” is to be understood here in a special rather than in a general sense. As far as mere numbers are concerned, there is often a large community of bees building their cells in close proximity all at the same time, but each builds its cell for itself alone, or rather for its family—no one thinks of helping its neighbour. There is no co-operation, in fact, and that makes all the difference. It would be all the same to every one of the bees that are building so close together if all the rest went away and left it to work alone. And yet we cannot even quite say this, because,in one case, at any rate, though every individual bee makes its own cell and thinks only of that and of its own family, yet, when all the cells are finished, the whole community join in making one mud roof over the whole of them. By this we see how difficult it is to find quite separate places for allied animals, and how the habits of one are apt to slide gradually into those of another. Still, we must do the best we can, and take words as we find them, remembering that the locusts, as already explained, donotbelong to thelocustidæ.
DRIVEN OUT BY HORNETS.
DRIVEN OUT BY HORNETS.
DRIVEN OUT BY HORNETS.
Aelian, in his “Natural History,” says that a city in Crete was attacked by such a plague of hornets that the inhabitants were driven to abandon it, and build a new city on another site. A hornet is shown to the right of this inscription.
Amongst the best known of the solitary species of bees are the Carpenter Bees, the Carding and Tapestry Bees, and the Mason Bees. Of the latter a great French observer, who, though he lives now, belongs really to the days of Réaumur and Swammerdam, has something to tell us. Speaking not of Réaumur’s maison bee—that “splendid Hymenopteron with its dark violet wings and costume of black velvet”[86]—but of a smaller species—Chalicodoma sicula—he says: “You should see the active bee at work when the road is dazzling white in the hot sunshine. Between the neighbouring farm where she is building and the road where the mortar is prepared there is a deep hum of the bees perpetually crossing each other as they come and go. The air seems traversed by constant trails of smoke, so rapid and direct is their flight. Those who go carry away a pellet of mortar as big as small shot: those who come settle on the hardest and driest spots. Their whole body vibrates as they scratch with the tips of their mandibles and rake with their forefeet to extract atoms of earth and grains of sand, which,being rolled between their teeth, become moist with saliva, and unite. They work with such ardour that they will let themselves be crushed under the foot of a passer-by rather than move.”[86]Then comes the making of the actual nest, or little collection of cells. “After choosing a boulder,” says Fabre, “she comes with a pellet of mortar in her mandibles, and arranges it in a ring on the surface of the pebble. The forefeet, and, above all, the mandibles, which are her most important tools, work the material, which is kept plastic by the gradually disgorged saliva. To consolidate the unbaked clay, angular pieces of gravel as large as a small bean are worked in singly on the outside of the still soft mass. This is the foundation of the edifice. Other layers are added, until the cell has the required height of three or four centimetres. The masonry is formed by stones laid on one another and cemented with lime, and can stand comparison with our own. Layers of mortar sparingly used hold them together. The cell completed, the bee sets to work at once to store it. The neighbouring flowers, especially those ofGenista scorpius, which in May turn the alluviums of the torrents golden, furnish sugared liquids and pollen. She comes with her crop swelled with honey, and all yellow underneath with pollen dust, and plunges head first into the cell, where for some moments one may see her work her body in a way which tells that she is disgorging honey. Her crop emptied, she comes out, but only to go in again at once, this time backwards. With her two hind feet she now frees herself from her load of pollen by brushing herself underneath. Again she goes out, and returns head first.She must stir the materials with her mandibles for a spoon, and mix all thoroughly together. When the cell is half full it is stored; an egg must be laid on the honey paste, and the door has to be closed. This is all done without delay. The orifice is closed by a cover of undiluted mortar, worked from the circumference to the centre. Two days, at most, seem required for the whole work.”[86]Afterwards several more cells—making a continuous group of from six to ten—are added, and when all is completed, the mason bee “builds a thick cover over the whole group, which, being of a material impermeable to water, and almost a non-conductor, is at once a defence against heat and cold and damp. This material is the usual mortar, made of earth and saliva, only with no small stones in it. The nest is now a rude dome, about as big as half an orange; one would take it for a clod of mud flung against a stone, where it had dried. Nothing outside betrays its contents—no suggestion of cells, none of labour. To the ordinary eye it is only a chance splash of mud.”
Of course, when the eggs are hatched, the bee larvæ feed on the stored pollen and honey, a pleasing picture which suggests another something like it, though not altogether the same. I allude to certain species of solitary wasps, which, urged by the same feelings of maternal solicitude, choose a living caterpillar, grasshopper, spider, etc., for the future sustenance of their young. Take, for instance,Ammophila urnariaof North America, whose habits in this respect have been carefully studied. This wasp is about an inch long, with very long legs, and awaist even exaggeratedly wasp-like. It is black in colour, but with a red mark running round the fore part of the abdomen. At the proper time she—for, of course, we are dealing with the female—may be seen running about the ground, and eagerly searching the various plants and grasses that come in her way. Occasionally, as though in lightness both of heart and body, she gives a leap off the ground, and at other times will fly up from it more deliberately, to make an examination of some overhanging leaf. At last, as a result of these little aerial excursions, let us say, she knocks down a certain green caterpillar of the kind wanted, and with maternal devotion full upon her, at once sets to work. The caterpillar, however, though taken by surprise, and assaulted the instant it has touched the ground, resists strenuously, as though instinctively knowing, and highly disapproving of, the fate in store for it. It is larger and more bulky than the wasp, and its contortions are so powerful that the latter is several times repulsed in her assaults. She is not discouraged, however, but continues perseveringly to fly at the caterpillar, till at last she takes it at a disadvantage, possibly in a moment of weariness, and alighting with her long legs on each side of the large, soft body, seizes it by the neck with her mandibles, and holds it fast. Now the caterpillar, stimulated doubtless by the painful, or at least unwelcome nip, struggles with redoubled energy; but it is beneath its oppressor, who, straddling over it and never relaxing her grasp, lifts it at last, with an effort, a little from the ground, and inserting her curved abdomen like a fish hook beneath it, strikes ina more effective and certain way than did ever the most benevolently contemplative member of all the fishing fraternity. The result is instantly apparent, for with the entry of that deadly sting into its body, all struggles on the part of the caterpillar cease, and it lies a living corpse at the feet of its cruel oppressor. The latter, after remaining still for some moments as though to give her victim time to realise and appreciate its situation, stings it again and then again, each time choosing, as she has done before, for the locality of the operation, the junction of two out of the dozen or so segments into which the long length of the caterpillar is divided. Then she flies up, but after circling a little above the scene of her triumph, she descends again, and gives her victim, though now helpless and paralysed, a taste or two more of her quality. The first part of her business is now done, and well done. She has earned a rest, or rather she may exchange one form of activity for another. Accordingly she proceeds to indulge in the pleasures of the toilette, and it is not till this is completely finished that she flies with, or drags, her victim to the neat little burial-place, representing also her future nursery, which she has already provided for it.[87]
The above illustration is taken from the account of a particular case which fell under the keen observation of G. W. and E. G. Peckham, two well-known American entomologists. On other occasions, however, this wasp—that is to say, various individuals of the same species—besides stinging the caterpillar, went through another and more curious process. This consisted in biting and squeezingthe anterior upper portion—the neck as we may call it—of their victim.[87]The same operation was also observed by Fabre when he watched his good mothers, but though I have called it biting and squeezing, that is not the right term for asavantto employ.Hecalls it malaxation, which, perhaps, means doing both at the same time. Biting, however, would seem to imply no less, but, perhaps in order to bite scientifically, it is necessary to take a piece out, or at least to make the blood come, though in common parlance this does not, or did not, hold good, since Sampson bit his thumb at Abram and Balthasar, in the first scene ofRomeo and Juliet, but it cannot be supposed—nor does the context support such a view—that he bit it so hard as that. Malaxation, however, let it be; but why such a process on the part of the wasp should be necessary it is not easy to see, since the mandibles are not poisonous like the sting, and the latter is all in all sufficient to produce the paralysis required, as is apparent in the instance already given, where the sting alone was employed. To me it seems possible that this malaxation may be a happiness to the wasp merely, as the shaking of a rat certainly is to a terrier, whatever other advantages accrue from it. That insects, like other animals, including man—who, indeed, is the crowning instance—take a savage pleasure in overpowering and killing their prey, I have myself very little doubt.
We have seen that this wasp stung the caterpillar between the segments of its body, and, as we will assume—for the result seems to warrant the inference—in the central part of it, so that the sting, entering the greatnervous cord or ganglion, which is situated in this region, with little swellings at each of the segmental rings, produced the described paralysis. It was Fabre’s view that this must always be the case, and he thought likewise, in accordance with his own observation, that the caterpillar received a sting at the junction of all or nearly all the segments of its body. Otherwise it would be imperfectly stung, and in consequence not sufficiently paralysed to prevent its struggling, and so detaching the young larva, or perhaps the egg, which, as it would seem, is laid on, and not inside, the body of its living provisions. On the other hand, were the caterpillar stung too severely, so as to be killed outright, the grub when hatched would only have putrid meat to feed upon, and this again, it was assumed, would be fatal to its existence. On these grounds Fabre concluded that we had here an instinct which must have been perfect from the beginning, since as anything short of such perfection would be followed by the death of the larva, those gradual steps by which, on the theory of natural selection, all excellence either of structure or instinct has been attained, could not in a case like this have had any existence.
But all this has been exploded by subsequent observation. What Fabre saw he knew, but in all that he inferred without seeing he was entirely mistaken. As observed by the Peckhams, a caterpillar may be either stung so slightly as to be quite lively, and yet not succeed in shaking off the wasp larva hatched on its body, or so severely as to die almost immediately, yet without detriment to the larva who feeds on its discoloured andmore or less putrified body, with the same gusto, and apparent benefit, as though it were warm with life.[87]Thus the question seems not so much to be, how can such perfection of instinct as was observed by Fabre have been attained through the process of natural selection, as why it should have been attained; or perhaps we may even go further and ask if this supposed perfection exists at all, and whether Fabre did not deceive himself. A wasp having secured a caterpillar is, of course, at liberty to sting it as often as it pleases. Why, then, should one wasp behave quite like another one in this respect? Here, as elsewhere, there would be some amount—perhaps a considerable amount—of variation in individual disposition, and wasps of milder or less savage mood would sting less frequently than their fiercer fellows. There might, therefore, as it appears to me, be a large amount of fluctuation both in the number and degree of severity of the stings—if indeed there is any regulation in this respect—and also in the consequent injury to the caterpillar or other insect, without any particular scope being offered for natural selection to play a part. What room, indeed, for such a force can there be if it makes no difference to the wasp-grub whether the caterpillar which is to be its food, is stung badly or slightly, or whether it lives or dies?
That this is really the case seems to be implied in the following paragraph which I quote from the same interesting work that I have before referred to[87]“The conclusions that we draw from the study of this genus differ in the most striking manner from those of Fabre.The one pre-eminent, unmistakable, and ever-present fact” (the invariable fact, as one might say) “is variability. Variability in every particular—in the shape of the nest and the manner of digging it, in the condition of the nest (whether closed or open) when left temporarily, in the method of stinging the prey, in the degree of malaxation, in the manner of carrying the victim, in the way of closing the nest, and last and most important of all, in the condition produced in the victims of the stinging, some of them dying and becoming ‘veritable cadavers,’ to use an expressive term of Fabre’s, long before the larva is ready to begin on them, while others live long past the time at which they would have been attacked and destroyed if we had not interfered with the natural course of events. And all this variability we get from the study of nine wasps and fifteen caterpillars”![87]Fabre’s ideas therefore seem totally disproved, but though natural selection—the counter-theory to his own—has no doubt produced theSphexandAmmophila, with their habit of stinging and storing caterpillars, to serve as food for their young, it does not follow that it has done anything more than this; for though variation be the stuff in which natural selection works, it need not always work in it—any more than a tailor need always make clothes because there is an abundance of cloth.
SOLITARY WASPS
SOLITARY WASPS
SOLITARY WASPS
In the upper part of the picture a solitary wasp is seen attacking a caterpillar on a leaf. Beneath is another of the same species busy pounding the entrance to its burrow with a pebble.
In the digging and closing of her burrow—her nesting-habits, as we may call them—ourAmmophilais almost as interesting to watch as in her mode of proceeding with caterpillars, though here a certain well-knownstimulus to human enjoyment which I need not enlarge upon is wanting. Having found a convenient spot for her nursery, she digs, with her mandibles and front pair of legs, a little tunnel in the ground, to about the length of her own body, and at the end of it hollows out a round chamber or cavern just large enough to make comfortable quarters for a pair of invalid caterpillars—a hospital for incurables, we may call it to begin with, but soon to become their tomb. Having dug to about her middle, the wasp backs out, with a little pellet of collected earth held firmly in her mandibles. With this she flies to a little distance and then, letting it drop, alights on the ground and takes a little rest before returning to continue her work. She may either fly or run back, for her legs are as highly developed as her wings—she is in fact a very perfect athlete. The process of excavation is now continued, there is more burrowing, more flying away with the earth dug out, and before long the nursery-vault is completed. The next thing is to find caterpillars for it, but before flying away to look for one,Ammophilacarefully conceals the entrance to her tunnel with pellets of earth, which she often brings from a distance, and will not be satisfied with unless they seem well adapted for their purpose. At last, when the aperture is both blocked and hidden, she starts off upon the still more important undertaking which has been already described, and after a longer or shorter interval—if her quest is successful—returns with a nicely stung caterpillar. As two are required there must be another journey and another stopping up of the burrow, before the final one,which is of a more solid nature, occupying, sometimes, as much as twenty minutes. In thus bringing her labours to a conclusion,Ammophilaoften shows a wonderful degree of intelligent foresight—foresight we must term it if we admit the intelligence; for sometimes she will drag a leaf over the entrance to the tunnel, though now filled in, or taking a stone as large as her head in her mandibles, will pound down the earth with it to make it firm and compact.[87]
It used to be said—and may be still by that large class of people who are for ever making false parallels and artificial distinctions—that man was the only animal that made intelligent use of an instrument, but Darwin instanced a monkey cracking a nut with a stone, and an elephant breaking off a bough to fan itself with. Here, in an insect, we have a case which is perhaps even more to the point—more extraordinary, that is to say; for certainly the idea of flattening and pressing down earth over a general surface, and of taking something to do it with, seems a little less obvious than that of cracking a nut, in a similar manner, and therefore to require more thought in the planner of such a process. No wonder that the delighted witnesses of this interesting fact flung themselves on the ground on each side of the unconscious inspirer of their wonder, in order to have a better sight of it; but that a previous observer of the same thing should have waited a year before publishing what he had seen, because he feared such a statement would not be believed,[87]is to my mind a display of prudence almost as wonderful, though not nearly soedifying, as that ofAmmophilaherself. If we are not to make known what we see, because people who believe in their own and nobody else’s eyesight are not likely to credit it, how is evidence to accumulate for the benefit of the more intelligent part of the community? It is only of this small minority that we should think, or, rather, we should not think of anything but the truth, where truth is concerned.
Returning to bees of the solitary kind, “the operations of the wood-piercers,” says Bingley, “merit our careful attention.” They shall have it for a moment, but space is against them. However, the female of the species,Xylocopa violacea, which for some reason is disliked by householders, bores in the springtime, by the aid of her strong mandibles alone, neat little circular tunnels in such objects as garden-seats, gates, front doors, arbours, window-shutters, rustic tables, and the like. At first, it is stated, she “bores perpendicularly, but when she has advanced about half an inch she changes her direction, and then proceeds nearly parallel with its sides for twelve or fifteen inches. If the wood of the seat, door, table, etc., be sufficiently thick, she sometimes forms three or four of these long holes in its interior, a labour which for a single insect seems prodigious, and in the execution of it some weeks are sometimes employed. On the ground, for about a foot from the place in which one of these bees is working, little heaps of timber-dust are to be seen. These heaps daily increase in size, and the particles that compose them are almost as large as those produced by a hand-saw.”[88]When the tunnels are finished, the mother bee dividesthem into some dozen little rooms about an inch deep, making the divisions of wood-dust, which she cements together by aid of a glutinous secretion with which she is furnished. Before each cell is closed it is filled with a paste composed of the farina of flowers, mixed with honey (it makes one envy the grub), and an egg is deposited in it. As each cell takes some time to make and provision, it is obvious that the egg in the lower one will hatch a little sooner than the one above it, and so on right up to the top. If, therefore, any one of the larvæ “were to force its way upwards, which it could easily do, it would not only disturb, but would infallibly destroy all those lodged in the superior cells.”[88]Here, however, natural selection (called Providence in Bingley’s time) steps in, and “has wisely prevented this devastation, for the head of the nymph (chrysalis), and consequently of the emerging bee, is always placed in a downward direction.”[88]Of course, therefore, the insect moves forward in the direction towards which it looks at birth—its new birth, that is to say; and, moreover—this is the really astonishing thing—“the mother digs a hole at the bottom of the long tube, which makes a communication between the undermost cell and the open air. By this contrivance, as all the bees instinctively endeavour to cut their way downward, they find an easy and convenient passage, for they have only to pierce the floor of their cells in order to make their escape, and this they do with their teeth very readily.” As regards this communicating passage, however, it is presumably a mere continuation of the tunnel, and wasprobably once occupied with cells, like the upper portion. Why the lower end of the tunnel should have come in time to be left empty—what advantage, that is to say, its being so represents—it is not easy to see, but possibly it stood in danger of being reached by a bird’s beak, through what has now become the exit of escape merely.
As there is a leaf-cutting ant, so, too, there is a leaf-cutting bee, but here the resemblance ends, since no thought of food or fungus enters the mind of the latter insect. Her more simple and direct object is to make the severed leaves into cells, and this she does with wonderful skill and ingenuity. The cells, which are made by rolling the pieces of leaves round within a tunnel or gallery, previously excavated in the earth, are separated from one another by a circular piece, which fits into the tube with extreme nicety, making at once the ceiling of each lower compartment and the floor of that above it. As each is finished the bee, as in the other instances, fills it with a mixture of honey and pollen, upon which she then lays an egg, and finally closes the mouth of the tunnel. The leaf principally used for the manufacture of these pretty cradles is the rose leaf, and the paste which fills them is of a rose-red colour, owing to the pollen having been collected for the most part from thistles.
The children of the leaf-cutting bee, therefore, are delicately housed, but what are they, in this respect, to those of the poppy or tapestry bee, who are born like the Byzantine princes in a “purple[89]chamber” made of therich leaves of poppies? Here they lie, or crawl, in state, one to each royal apartment, which is filled, almost to the brim, with the sweet food of bees. Yet when they come forth, at last, it is not as gorgeous imperial creatures clothed in “purple and pall,” but only little ordinary-looking black bees covered all over with dirty grey hair. And their beautiful purple poppy chamber has been seen by no one—not even by themselves probably—buried as it is full three inches deep in the earth. Wallace, somewhere in hisMalay Archipelago, moralises over the beautiful little kingbird of paradise, sparkling out its life amidst the forest solitudes of a remote island, unseen by human eyes, save those of savages, till once or twice, perhaps, in a century, some wandering white man, who alone is capable of appreciating its beauty, comes to bang its life out and bear away its skin. The thought of this dainty little crimson-tapestried bower lying in black darkness, like a grave beneath one’s feet, rouses a similar train of reflection in the mind, but perhaps it would do so more strongly were it associated in the same degree with ideas of sport or profitable collecting.
The carding-bee is interesting, not so much for the nest which it makes, as for the wonderful way in which it makes it—or, to express it more justly, it is more especially interesting on this account. Having either made or found a suitable cavity, these bees under-roof it with a thick thatching of moss. To carry this, bit by bit, to the place, would take them a very long time, so, instead of doing so, they stand one behind another, with their backs toward the nest, in a line that reaches from the moss toits entrance. The furthest bee then pulls out a piece with her mandibles, cards it with her fore feet, and, with the others, passes it on, beneath her body, to the second bee, who passes it to the third, the third to the fourth, and so on, all down the line, the last bee entering the nest with it. Thus these bees do with moss exactly what rats have been seen to do with eggs, when transporting them to their burrows. A most interesting anecdote of this is quoted by Romanes,[90]from Jesse’sGleanings, but it does not appear to be in my edition, which I had thought was a complete one. All I can find is a bare reference to their having been known to “convey” eggs from a box, in this way—“convey the wise it call.” This is an annoying discovery, for I detest all selections, not made by myself, from Palgrave’sGolden Treasuryto any man’s “Hundred Rest Books.” But if my editionisa complete one, then the thing should be looked into, for the anecdote quoted by Romanes is not there—at least it is untraceable through the index.
Like ants, bees are subject to parasites, and as some belonging to the former are ants themselves, so with bees we have the same thing, but developed to a still more striking extent; for there is no ant that I know of that lives with another which it so closely resembles that the latter is unable to distinguish it from itself. Such bees, however, there are. Some of our humble bees, for instance, go through life thus attended by a double whose existence it never for one moment suspects. The two, indeed, are linked in the closest bonds of social intimacy. Together they leave the nest, together they fly from flower toflower, together they re-enter it. Together, too, they seem to glow in industry—to emulate each other’s toil. But all the while that the true industrious bee is collecting pollen and nectar the double is only pretending to do so—or rather, let us say, seeming—and whilst the former bustles about, feeding the larvæ and making the cells, the latter only bustles about, like the shadow of a busy person on the wall. But when the true bee lays an egg, the double lays one too, almost at the same moment, and in the very same cell. Both are then hatched, together, and the two larvæ grow up in the same cradle, nourished by the same food, make their transformation side by side, and so creep forth into the nest. The two, as I say, are hardly to be distinguished one from another, yet all the while one is a real true-hearted humble bee, and the other a mere show, a stage make-up, an outer shell without any of the proper qualities inside. And the best of the joke is, that, probably, the false or cuckoo bee, as it is called, is as much deceived as its foster relatives, and imagines itself a good honest sterling member of the community. It is forced by nature to cheat, but the fraud is unconscious, and the impostor is imposed on in its turn.
Thus in the insect world we have something which can only be brought about, amongst ourselves, through a conscious disguise, by means of wigs, false moustaches, etc.—what we call an impersonation—but here is a life-long impersonation which costs the “born actor” no trouble. Why is this? What is the meaning of it? Why should one bee—or any other insect or creature—look just like another one, and yet have a Latin name of its own, whichthe other has no right to? Why should the individuals of one species be hardly more like each other than they are like the individuals of another species, even though—as is often the case—these two species are widely separated in the system of nature? Such are the questions to which a consideration of these cuckoo-bees, as they are called, give rise. They will be answered, if at all, in the following chapter.