CHAPTER XVI
From wood to ambrosia—Wood-boring beetles—Rival claimants—Stag and other beetles—Metempsychosis—Flies with horns—Comical combatants—Female encouragement—The sacred Scarabæus—A beetle with a profession—Table companions—Old and new fallacies—From theft to partnership.
IT is, no doubt, through feeding on wood that the beetles we have been considering came in time to feed on ambrosia. The particular fungus, that is to say, which for some unaccountable reason has received this name, appeared as a natural growth upon the walls of their tunnels, and in time it came to be thought necessary, and its coming was arranged for. By similar steps, probably, the leaves once carried as food to their nests by the sauba ants, or cooshies, have become the soil merely on which that food is grown; and so I have no doubt myself that even if the present agricultural ants of Texas do not purposely sow and afterwards reap the rice that springs up around the circular mound of their domicile, their descendants will do so. Indeed, it seems rather curious that, with such facilities for a gradual development, the habit has not yet been acquired; and this is the chief reason which inclines me to suspend judgment on the question, and wait for further observations. Far from thinking the thing too wonderful, I wonder if it be not the case. Such wonder, however, is for ants and not forbeetles, except, indeed, ambrosia beetles, who certainly merit it, though in an opposite way. No other wood-borers of the order are anything but wood-eaters, or, at any rate, if a few feed on fungus, as would not be improbable, should it happen to appear, they have nothing to do with the cultivation of it. The words “as far as we know,” however, must be added to the foregoing statement. Numbers of beetles pass the larval and pupal stage of their existence within the trunk of a decaying or even of a perfectly sound tree, from which they issue after the final metamorphosis has been made. Amongst these is our own stag-beetle, in whom, that is to say in whose caterpillar, some suppose themselves to see theCossusof the ancient Romans, which was as much appreciated by them, and, no doubt, justly, as are earthworms by the Chinese. Others, however, believe this to have been the large red meaty-looking caterpillar of the goat-moth; and as the one conjecture is quite as plausible as the other, the only, or, at any rate, the best way of arriving at a conclusion would be to try them both—a simple plan which, as far as I know, has not yet been adopted.
The stag-beetle—when of maximum size, that is to say, for it varies amazingly in this respect—is much the largest beetle which this our island possesses, but though, with its huge, antler-like jaws, it makes a good perennial illustration for all books of popular entomology, its merits seem to end there, for either there is nothing or nothing has yet been observed particularly interesting about it. No doubt, if we look at the matter from an absolute rather than a relative point of view, the second of these twoexplanations is the correct one, for a creature has only to be studied in order to become interesting; but as compared with ants, bees, wasps, and many other insects, beetles, or, at any rate, the vast majority of them, are not so very entertaining in their habits, and the stag-beetle has no superiority in this respect to correspond with its size and uncommon appearance. This appearance, however, is confined to the male, who alone possesses the great branching mandibles on which its greater size also is largely dependent. It would be natural to suppose that these formidable weapons, as they certainly appear, stood in relation to the combats of the males for the possession of the females, yet it is often stated that the short, sharp pincers of the latter, which can be made, it would seem—anyone who doubts may try—to meet in the flesh, are really the more efficient of the two. Be this as it may, it is not improbable that the stag-beetle’s jaws, since they are very handsome, may have been developed less as weapons than as ornaments, under the laws of sexual selection. Darwin, if I remember, was doubtfully of this opinion, and he attributes many strange projections and processes on the head or thorax of other beetles—as notably that huge one with a snout like a weaver’s beam, called the Hercules beetle—to the same agency. No use for this extraordinary trunk, as one may term it, has as yet been discovered, but as the under portion is covered with a thick matting of soft brown hairs, it would seem as though it had some office to perform, unless indeed we suppose thischevelureto be likewise admired. A lesser, though still tremendous, projection, starting from thehead, as the other one does from the thorax, is likewise unaccounted for, for though the two together make in appearance a pair of uncouth and irregular pincers, they neither are, nor apparently can be used in this way. Nothing appears to be known of this strange creature’s habits, and the same may be said in regard to most of the more remarkable-looking beetles of the world, as well as those which are not so extraordinary in their appearance. The ways of beetles, in fact, have been but little studied, and it is perhaps not too much to say that if for every thousand that fill the show-cases in museums we could know the life-history of one, we might with infinite advantage, in exchange for this knowledge, throw the whole pin-forest of them into the sea. In what light this fact, if true, exhibits the labours of those naturalists—as the world calls them—who, living for years amidst the life-teeming regions of the earth, have spent their whole time in constantly killing and killing, coming home, at last, with an acre of carcasses, to write a book containing hardly anything of first-hand observation—the soul of natural history—I will not pause to inquire.
THE HERCULES BEETLE.The enormous beetle from which this illustration was drawn, though not a particularly large specimen, is six inches long, and the upper jaw measures three inches and a half.
THE HERCULES BEETLE.The enormous beetle from which this illustration was drawn, though not a particularly large specimen, is six inches long, and the upper jaw measures three inches and a half.
THE HERCULES BEETLE.The enormous beetle from which this illustration was drawn, though not a particularly large specimen, is six inches long, and the upper jaw measures three inches and a half.
There are many other species of beetles, the males of which are ornamented about the head and thorax with all sorts of knobs and projections, so that, with some, one might think that a one-horned or two-horned rhinoceros had undergone metempsychosis, as it is called, that its soul, that is to say, had transmigrated into the body of an insect, which latter had been fashioned so as fancifully to resemble its old one. However, as this would be a downward journey, it is more satisfactory to imaginethat certain beetles have been “translated” into rhinoceroses. As to these kinds of excrescences, Darwin believed them to be of the nature of adornments, and since their owners—the males—have not been seen to use them in warfare, and indeed do not appear to fight, it is difficult to imagine any otherraison d’êtrefor them. This seems all the more likely because certain flies found in the Malay Archipelago have likewise excrescences, which we have to call horns, and these too are confined to the males, though it is hardly to be imagined that they would fight in a manner to make them of service. These flies must be most extraordinary creatures to look at. They have long legs, which they draw together underneath them, so as to stand very high, and their horns are not only conspicuous by their size and shape, but also by being brightly coloured. Thus in one species they are a beautiful pink with a light stripe down the centre, and bordered on each side with black. In another the colours are yellow, black, and brown, and thoughElaphomia cervicornishas to be contented with black, and pale tips, yet his are the finest pair of all, being nearly as long as his body, and branched so as to look like a pair of slender and delicate stag’s horns. The other pairs are not like this, one of them being rather club-shaped, and therefore less horn-like, whilst another has an extraordinary resemblance to the antlers of an elk, which are broad and palmated, so thatitis theElaphomia alcicornis. Here, therefore, are both horned beetles and horned flies who yet do not fight with their horns, so that unless they serve as ornaments it would be a puzzle to say what theydo serve as; for as the male beetles do not fight, which is the principal way in which male creatures, including man, show their vigour, why should we suppose them to be more vigorous than the females?
In some other beetles, which do fight, the sexes do not differ conspicuously, nor do their facial or other peculiarities appear to bear any special relation to warfare. Thus “those curious little beetles, theBrenthidæ” of the Malay Archipelago, have an extraordinarily long snout—or rostrum, to talk entomologically—at the end of which come the jaws and antennæ, and this rostrum is used by the female to bore holes in decaying wood, where she afterwards deposits her eggs. The males, however, do what they can with them as weapons, and Dr. Wallace has seen two of them fighting together in a very comic manner. “Each,” he tells us, “had a fore-leg laid across the neck of the other, and the rostrum bent quite in an attitude of defiance, and looking most ridiculous.”[70]On another occasion “two were fighting for a female, who stood close by busy at her boring. They pushed at each other with their rostra, and clawed and thumped, apparently in the greatest rage, although their coats of mail must have saved both from injury. The small one, however, soon ran away, acknowledging himself vanquished.”[70]Lethrus cephalotesis another fighting beetle, and here the males, instead of horns or anything extraordinary, have merely somewhat larger mandibles than the females. “The two sexes,” says Darwin, “inhabit the same burrow. If, during the breeding season, a strange male attempts to enter the burrow he is attacked;the female does not remain passive, but closes the mouth of the burrow and encourages her mate by continually pushing him on from behind; and the battle lasts until the aggressor is killed or runs away.”[71]
Of yet another species, theAteuchus cicatricosus, the sexes “live in pairs, and seem much attached to each other; the male excites the female to roll the balls of dung in which the ova are deposited, and if she is removed he becomes much agitated. If the male is removed the female ceases all work, and, as M. Brulerie believes, would remain on the same spot until she died.”[72]But M. Brulerie was reckoning apparently without M. Fabre, since whose investigations in this last department it may be said that “nous avons changé tout cela.” For thisAteuchusis none other than the celebrated Scarabæus, or sacred beetle, and, in the first place, M. Fabre has shown that the balls of dung, which are rolled about by them with so much perseverance and energy, do not contain the ova, as it was always thought that they did, but are merely provender and nothing more, and though sometimes they are rolled by two beetles together, these are not the male and female, or, at any rate, they need not be. They are just as likely to be two males or two females, and in any case, though the two may be of opposite sexes, they do not represent a mated pair. Simply when the two—if, as is by no means always the case, more than one take part in the rolling—have pulled and pushed the ball to a suitable place, they make a hole in the ground, into which they drag it, and, having closed the aperture, sit and feast at their leisure.
According to Fabre the vital principle contained in the egg would be destroyed were it rolled about in this fashion, so when the mother Scarabæus, who, it would appear, works in this matter alone, is ready to lay her eggs, she first makes an excavation, and then brings the dung down into it in pellets, till there is a heap of it, which fills the whole concern. Then “the first thing to do is to select very carefully, taking what is most delicate for the inner layers, upon which the larva will feed, and the coarser for the outer ones, which merely serve as a protecting shell. There around a central hollow which receives the egg the materials must be arranged layer after layer, according to their decreasing fineness and nutritive value; the strata must be made consistent, and adhere one to another; and finally the bits of fibre in the outside crust, which has to protect the whole thing, must be felted together.”[73]
Thus, when the grub first issues from the egg, it finds light digestible food ready to hand, which becomes coarser and more fibrous with its growth and increased capacity of assimilating such stronger diet. As more and more is eaten, the ball, which is about the size of an ordinary apple, becomes hollower and hollower, till at last, when only the outer crust remains, the grub is ready to enter upon that wonderful series of changes—called its metamorphoses—which will bring it forth into this larger ball of dirt, a complete beetle, with a useful profession, that of scavenger, immediately open to it.
Thus a fallacy which, according to Fabre, dates from the time of the Pharaohs, viz. that every ball of dungwhich one might at any time see a Scarabæus beetle rolling and trundling along contained its egg, has been finally disposed of, nor is this the only one. It used to be thought, not only that any two beetles rolling a ball between them were male and female, but also that any single one that happened to be in difficulties would immediately fly off and summon a comrade or two to its aid. Fabre denies this altogether, and maintains that in this rolling away of provisions each individual beetle is purely a self-seeker. It is true, as we have seen, that thebonne bouchewill often be eaten by two Scarabæi—never more—in the cavern prepared beforehand for its reception, but, according to Fabre, this is only because it is to the mutual interest of both to act in this way, since neither can succeed in appropriating the ball to itself, in spite of efforts—which in other cases, however, may be successful—to do so.
In all such cases the one beetle is the real owner of the ball, whilst the other is only there with the intention of stealing it if he can. Thus the thief will often let himself be pushed along by the honest worker, lying flat on the ball, and doing no work whatever, though at other times, when a rise in the ground makes it difficult for a single beetle to roll it, he will assist with all his power. Again, whilst the one Scarabæus is hollowing out a cave for the approaching banquet to take place in, the other, left with the ball, will, after some time, begin to go off with it alone, and unless pursued by the owner before he has gone too far, he accomplishes his purpose, and eats it all himself. Thus he has associated himself to the maker of the ball with the distinct idea of stealing it if he can.He has this plot in his mind, to pretend partnership, to even give real assistance, but to watch his opportunity and decamp when it occurs. That, at least, is the view suggested for our adoption, but I cannot say that it recommends itself to me. Fabre, in my opinion, has disposed of one error only to fall into another of precisely the same kind. He says very justly in regard to the idea that one beetle would deliberately fly away and summon others to its assistance, “It is no slight thing to admit that an insect has a truly surprising grasp of the situation, and a facility for communicating its ideas to others of its kind more surprising still. Are we to suppose that a Scarabæus in distress conceives the idea of begging for help, flies off, explores the country round, etc.?” Very true; but if we are not to suppose this, I certainly will not suppose, either, that this same Scarabæus can conceive the idea of pretending to assist another in order to rob him of his property. This would be as deep a laid scheme as the other, and the facts of the case, as given by Fabre himself, do not appear to me to lend themselves to such an explanation.
The point of these interesting relations has been, in my opinion, entirely missed. What we really see in them, or what, at least, is there for us to see, is the beginnings of order and social polity, evolving themselves out of lawlessness and the strong hand. Further, it has already gone some little way, for the fact that two Scarabæi do, as a matter of fact, assist each other very materially in rolling the ball, and that they do sit and eat it together in the same chamber, are not to be gotover by any such amusing fancy picture as this brilliant writer, as well as keen observer, has given us. It is no use fixing our eyes upon that part of the conduct of the beetle which we are invited to call the thief, in contradistinction to the owner—I doubt myself if Fabre has always kept the two distinct from beginning to end—if we pass over the other and much more interesting parts of it. Why does this beetle help to get the ball up a hill, and why does he sit for some considerable time with it outside the cave that the other is making, before he begins to go off with it? Does he say to himself, in the first case, “If we don’t get it to the right place, to begin with, he’ll never dig a hole and leave me outside with it,” and, in the second, “I’ll wait till he has come out and found it all right, several times, so that his suspicions may be put to sleep”? This would be scheming with a vengeance; butserviteur Monsieur Fabre, I must refer you to your own incredulity in another matter. I will never accept such an explanation, and the view which I take of the whole affair is this. The beetle which Fabre calls the thief is under the sway probably of precisely the same feeling as the other one—the rightful owner. He has seized a piece of dung, and as he seizes it, whether another has it at the time or not, it appears to be his, that being the only idea of rightful ownership which is not too large for his comprehension. Finding, however, that another beetle has exactly the same idea as himself, he is forced, willy nilly—and the experience is being constantly repeated—to accommodate himself to this circumstance and make the best of it. The ball—thisis the one great advantage—will continue to roll even if he does not push it. Therefore he can afford to be lazy sometimes, and be pushed along with it. The ball stops: in that case he must push it, and, even without this incentive, it would appear from Fabre’s account that the two often work together. Thus, from the very necessities of the case, it is evident that a sense of partnership—at least a feeling of doing work in combination with another—has begun to dawn in the mind of the Scarabæus. The fact that when the one beetle is left alone with the ball, whilst the other excavates, it does not immediately go off, but stays a little, as though waiting to be rejoined, suggests to my mind that this feeling, fostered by custom, has already gone some way, though it is not wonderful that, after a time, the primitive individualistic tendency should again assert itself. But when the fugitive is overtaken, it assists the other to roll the ball back, and the end of it all is a meal shared peacefully between the two, in one common apartment. If we suppose that the instinct, or capacity, of working together for some common end has had any beginning, surely we might expect to find it in some such state of affairs as this. The result of primitive conceptions is that two Scarabæi are often obliged to roll one ball between them, and if there be any advantage in this arrangement, natural selection will no doubt do the rest. That it has already begun to do it is, I think, very probable; but Fabre was not an evolutionist.