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 for beetles,
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 the _Cossus_ of 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 two explanations 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 this
_chevelure_ to be likewise admired. A lesser, though still tremendous,
projection, starting from the head, 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.
------------------------------------------------------------------------
[Illustration: 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 imagine that 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 other _raison d’être_ for 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 though
_Elaphomia cervicornis_ has 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 that _it_ is the _Elaphomia 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 they do 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, the
_Brenthidæ_” 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
cephalotes_ is 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, the _Ateuchus 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 this _Ateuchus_ is
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 dung which 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 the _bonne bouche_ will 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 got over 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; but _serviteur 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—this is
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.
-----
Footnote 70:
The Malay Archipelago.
Footnote 71:
Darwin, The Descent of Man, p. 300.
Footnote 72:
The Malay Archipelago.
Footnote 73:
Souvenirs Entomologiques.
------------------------------------------------------------------------