THE SACRED BEETLE IN CAPTIVITY
If we ransack the books for information about the habits of the
dung-rollers in general and the Sacred Beetle in particular, we find
that modern science still clings to some of the beliefs which were
current in the days of the Pharaohs. We are told that the ball which is
bumped across the fields contains an egg, that it is a cradle in which
the future larva is to find both board and lodging. The parents roll it
over hilly country to make it nice and round; and, when jolts and jars
and tumbles down steep places have shaped it properly, they bury it and
abandon it to the care of that great incubator, the earth.
So rough an upbringing has always seemed to me improbable. How could a
Beetle’s egg, that delicate thing, so sensitive under its soft wrapper,
survive the shaking-up which it would undergo in that rolling cradle?
In the germ is a spark of life which the least touch, the veriest
trifle can extinguish. Are we to believe that the parents would
deliberately bump it over hill and dale for hours? No, that is not the
way in which things happen; a mother does not subject her offspring to
the torture of a Regulus’ barrel.
However, something more than logic was needed to make a clean sweep of
accepted opinion. I therefore opened some hundreds of the pellets that
were being rolled along by the Dung-beetles; I opened others which I
took from holes dug before my eyes; and never once did I find either a
central cell or an egg in those pellets. They were invariably rough
lumps of food, fashioned in haste, with no definite internal structure,
merely so much provender with which the Beetle retires to spend a few
days in undisturbed gluttony. The dung-rollers covet and steal them
from one another with a keenness which they would certainly not display
in robbing one another of new family charges. For Sacred Beetles to go
stealing eggs would be an absurdity, each of them having quite enough
to do in securing the future of her own. So this point is henceforward
settled beyond question: the pellets which we see the Dung-beetles
rolling never contain eggs.
My first attempt to solve the knotty problem of the larva’s rearing
involved the construction of a spacious vivarium, with an artificial
soil of sand and a constant supply of provisions. Into this cage I put
some twenty Sacred Beetles, together with Copres, Gymnopleuri and
Onthophagi. No entomological experiment ever cost me so many
disappointments. The difficulty was the renewing of the food supply.
Now my landlord owned a stable and a Horse. I gained the confidence of
his man, who at first laughed at my proposals, but soon allowed himself
to be convinced by the sight of silver. Each of my insects’ breakfasts
came to twenty-five centimes. I am sure that no Beetle budget ever
amounted to such a sum before. Well, I can still see and I shall always
see Joseph, after grooming the Horse of a morning, put his head over
the garden-wall and, making a speaking-trumpet of his hand, call ‘Hi!’
to me in a whisper. I would hurry up to receive a potful of droppings.
Caution was necessary on both sides, as the sequel will show you. One
day the master happened to come up just when the transfer was being
made, and took it into his head that all his manure was going over the
wall and that what he wanted for his cabbages went to grow my verbenas
and narcissi. Vainly I tried to explain: he thought that I was being
funny. Poor Joseph was scolded, called all manner of names and
threatened with dismissal if it happened again. It didn’t.
I had one resource left, which was to go ignominiously along the
high-road and furtively collect my captives’ daily bread in a paper
bag. This I did and I am not ashamed of it. Sometimes fortune favoured
me: a Donkey carrying the produce of the Château-Renard or Barbentane
kitchen-gardens to the Avignon market would drop his contribution as he
passed my door. The gratuity, picked up instantly, made me rich for
several days. In short, by scheming, waiting, running about and playing
the diplomat for a blob of dung, I managed to feed my prisoners. If a
passion for one’s work and a love which nothing can discourage ensure
success, my experiment ought to have succeeded. It did not succeed.
After a time, my Sacred Beetles, pining for their native heath in a
space too limited for their elaborate evolutions, died miserable
deaths, without revealing their secrets. The Gymnopleuri and Onthophagi
were not so disappointing. At the proper time I shall make use of the
information which I obtained from them.
Together with my attempts at home breeding I carried on my direct
investigations abroad. The results fell far short of my wishes. One day
I decided that I must enlist outside help. As it happened, a merry band
of youngsters was crossing the plateau. It was a Thursday. [12]
Untroubled by thoughts of school and horrid lessons, they were coming
from the neighbouring village of Les Angles, with an apple in one hand
and a piece of bread in the other, and wending their way to the bare
hill yonder, where the bullets bury themselves harmlessly when the
garrison is at rifle-practice. The object of this early morning
expedition was the unearthing of a few bits of lead, worth perhaps a
halfpenny the lot. The small pink blossoms of the wild geranium decked
the scanty patches of grass which for a brief moment beautified this
Arabia Petræa; the Wheat-ear, in his black-and-white motley, twittered
as he flew from one rocky point to another; on the threshold of burrows
dug at the foot of the thyme-tufts, the Crickets were filling the air
with their droning symphony. And the children were rejoicing in this
springtide happiness and rejoicing still more in the prospect of
wealth, the halfpenny which they would receive for such bullets as they
found, the halfpenny which would enable them to buy two peppermint
bull’s-eyes next Sunday, two of the big ones, at a farthing apiece,
from the woman at the stall outside the church.
I accost the tallest, whose sharp face gives me some hope of him; the
little ones stand round, eating their apples. I explain what I want and
show them the Sacred Beetle rolling his ball; I tell them that in some
such ball, hidden somewhere or other underground, there is occasionally
a little hollow place and in that hollow a little worm. The thing to do
is to dig around at random, keeping an eye on what the Beetles are
doing, and to find the ball containing the worm. Balls without a worm
don’t count. And, to tempt them with a fabulous sum which shall divert
to my purposes the time hitherto devoted to a few farthings’ worth of
lead, I promise to pay a franc, a shiny new twenty-sou piece, for each
occupied ball. At the mention of this sum, those adorably innocent eyes
open their widest. I have upset all their ideas of finance by naming
this fanciful price. Then, to show that my proposal is serious, I
distribute a few sous as earnest-money. I arrange to be there next
week, on the same day and at the same time, and faithfully to perform
my part of the bargain towards all those who have made the lucky find.
After carefully posting the party in their duties, I dismiss them.
‘He means it!’ the children said, as they went away. ‘He really means
it! If only we could make a franc apiece!’
And their hearts swelling with fond hopes, they clinked the sous in
their hands. The flattened bullets were forgotten. I saw the children
scatter over the plain and begin their search.
On the appointed day, a week later, I returned to the plateau. I was
confident of success. My young helpers were sure to have spoken to
their playmates of this lucrative trade in Beetle-balls and convinced
the incredulous by displaying their earnest-money. And indeed I found a
larger party than the first time awaiting me on the spot. They came
running to meet me, but there was no burst of triumph, no shout of joy.
I suspected at once that things were going badly; and my suspicions
were but too well-founded. Many times, after coming out of school, they
had hunted for what I had described, but they had never discovered
anything like it. They handed me a few pellets found underground with
the Beetle, but these were simply masses of provisions, containing no
larva. I explained matters anew and made another appointment for the
following Thursday. Again the search was unsuccessful. The disheartened
little hunters were now reduced to quite a small number. I made a final
appeal to their sportsmanship and perseverance; but nothing came of it.
And I ended by compensating the most industrious, those who had held
out to the last, and cancelling the bargain. I had to conduct my own
researches, which, though apparently very simple, were in reality
extremely difficult.
Many years have passed since then, but even to-day I am without any
definite, consistent result after all my digging and exploring, though
I have made my examinations at the most likely spots and have carefully
watched for favourable opportunities. I am reduced to piecing together
my incomplete observations and filling up the gaps by analogy. [13] The
little that I have seen, combined with my study of other Dung-beetles
in captivity—Gymnopleuri, Copres and Onthophagi—is summed up in what
follows.
The ball which is destined to contain the egg is not made in public, in
the hurry and confusion of the dung-yard. It is a work of art and
supreme patience, demanding concentration and scrupulous care, both
alike impossible in the thick of the crowd. One needs solitude in order
to think out a plan of operations and set to work. So the mother digs
in the sand a burrow four to eight inches deep. It is a rather spacious
hall communicating with the outer world by a much narrower passage. The
insect brings into it carefully selected materials, doubtless in
spherical form. There must be many journeys, for towards the end of the
work the contents of the cell are out of all proportion to the size of
the entrance-door and could not be stored at one attempt. I remember a
Spanish Copris who, at the time of my inspection, was finishing a ball
as big as an orange at the far end of a burrow whose only communication
with the outside was by means of a gallery into which I was just able
to insert my finger. It is true that the Copres do not roll pills and
do not travel long distances to fetch food home. They dig a hole
immediately under the dung and drag the material backwards, armful by
armful, to the bottom of their well. They have thus no difficulty in
provisioning their houses; moreover, they work in security under the
shelter of the manure: two conditions that promote luxurious tastes.
The Dung-beetles that follow the humble trade of pill-rollers are less
extravagant; and yet, if he cares to make two or three journeys, the
Sacred Beetle can amass wealth of which the Spanish Copris might well
be jealous.
So far, the Beetle has only raw material, lumped together anyhow. A
minute sorting has to take place before anything else is done: this
stuff, the purest, is for the inner layer on which the grub will feed;
that other, coarser stuff is for the outer layers, which are not meant
for food and serve only as a protecting shell. Then, around a central
hollow which receives the egg, the materials must be arranged in
successive strata, according as they are less refined and less
nutritive; the layers must possess a proper consistency and must be
made to adhere to one another; last of all, the stringy parts of the
outer layers, which have to protect the whole structure, must be felted
together. How does the clumsy Sacred Beetle, who is so stiff in her
movements, accomplish a work of this kind in complete darkness, at the
bottom of a hole crammed with provisions and hardly leaving room to
stir? When I consider the delicacy of the workmanship and then the
rough tools of the worker—angular limbs capable of cutting into hard or
even rocky soil—I think of an Elephant trying to make lace. Let whoso
can explain this miracle of maternal industry; as for me, I give it up,
all the more as I have not had the luck to see the artist at work. We
will confine ourselves to describing her masterpiece.
The ball containing the egg is usually the size of an average apple. In
the centre is an oval hollow about two-fifths of an inch in diameter.
The egg is fixed at the bottom, standing perpendicularly; it is
cylindrical, rounded at both ends, yellowish-white and about as large
as a grain of wheat, but shorter. The inside of the niche is coated
with a shiny, greenish-brown, semifluid material, a real stercoral
cream, destined to form the larva’s first mouthfuls. To make this
dainty food, does the mother collect the quintessence of the dung? The
appearance of it tells me something different and makes me certain that
it is a pap prepared in the maternal stomach. The Pigeon softens the
grain in her crop and turns it into a sort of milky soup which she
subsequently disgorges to her brood. To all seeming, the Dung-beetle
displays the same solicitude: she half-digests choice provender and
disgorges it in the form of a meat-extract with which she lines the
walls of the cavity where the egg is laid. Thus the larva, on hatching,
finds an easily-digested food, which very soon strengthens its stomach
and enables it to attack the underlying strata, which have not been
refined in the same way. Under the semi-fluid paste is a soft,
well-compressed, uniform mass, from which every stringy particle is
excluded. Beyond this are the coarser layers, abounding in vegetable
fibres. Finally, the outside of the ball is composed of the commonest
materials, but packed and felted into a stout rind.
Manifestly we have here a progressive change of diet. On leaving the
egg, the frail grub licks the dainty broth on the walls of its cell.
There is not much of this, but it is strengthening and very nutritious.
The pap of earliest infancy is followed by the more solid food given to
the weaned nurseling, a sort of paste that stands midway between the
exquisitely delicate fare at the start and the coarse provisions at the
finish. There is a thick layer of it, enough to turn the infant into a
sturdy youngster. But now for the strong comes strong meat:
barley-bread with its husks, that is to say, natural droppings full of
sharp bits of hay. Of this the larva has enough and to spare; and, when
it has attained its full growth, there remains an enclosing layer. The
capacity of the dwelling has increased with the growth of the occupant,
fed on the very substance of the walls; the original little cell with
the very thick walls is now a big cell with walls only a few
millimetres in thickness; the inner layers have become larva, nymph or
Beetle, according to the period. Lastly, the ball itself is a stout
shell, protecting within its spacious interior the mysterious processes
of the metamorphosis.
I can go no farther, for lack of observations; my records of the birth
of the Sacred Beetle stop short at the egg. I have not seen the larva,
which however is known and is described in the text-books; [14] nor
have I seen the perfect insect while still enclosed in its chamber in
the ball, before it has had any practice in its duties as a pill-roller
and excavator. And this is just what I particularly wanted to see. I
should have liked to find the Dung-beetle in his native cell, recently
transformed, new to all labour, so as to examine the workman’s hand
before it started its work. I will tell you the reason for this wish.
Insects have at the end of each leg a sort of finger, or tarsus as it
is called, consisting of a succession of delicate parts which may be
compared with the joints of our fingers. They end in a hooked claw. One
finger to each leg: that is the rule; and this finger, at least with
the higher Beetles and notably the Dung-beetles, has five phalanges or
joints. Now, by a really strange exception, the Scarabs have no tarsi
on their front legs, while possessing very well-shaped ones, with five
joints apiece, on the two other pairs. They are maimed, crippled: they
lack, on their fore-limbs, that which in the insect very roughly
represents our hand. A similar anomaly occurs in the Onitis- and
Bubas-beetles, who also belong to the Dung-beetle family. Entomology
has long recorded this curious fact, without being able to offer a
satisfactory explanation. Is the creature born maimed, does it come
into the world without fingers to its forelimbs? Or does it lose them
by accident, once it is given over to its toilsome labours?
One could easily imagine this mutilation to be the result of the
insect’s hard work. Poking about, digging and raking and slicing, at
one time in the gravelly soil, at another in the stringy mass of
manure, do not constitute a task in which organs so delicate as the
tarsi can be employed without risk. And here is an even more serious
matter: when the Beetle is rolling his ball backwards, with his head
down, it is with the extremities of his fore-feet that he presses
against the ground. What might not happen to the insect’s feeble
fingers, slender as thread, in consequence of this continual rubbing
against the rough soil? They are merely useless encumbrances; one day
or other they seem bound to disappear, crushed, torn off, worn out in a
thousand ways. We know unfortunately that our own workmen are all too
frequently injured in handling heavy tools and lifting great weights;
even so might the Scarab be crippled in rolling his ball, an enormous
load to him. In that case his maimed arms would be a noble testimony to
his industrious life.
But straightway grave doubts begin to assail us. If these mutilations
were really accidental and the result of too strenuous work, they would
be the exception, not the rule. Because a workman or several workmen
have had a hand caught and crushed in a machine, it does not follow
that all the rest will also lose their hands. If the Scarab sometimes,
or even very frequently, loses his fore-fingers in pursuing his trade
as a pill-roller, there must be some at least who, more fortunate or
more skilful, have preserved their tarsi. Let us then consult the
actual facts. I have observed in very large numbers the various species
of Scarabs that inhabit France: Scarabæus sacer, who is common in
Provence; S. semipunctatus, who keeps fairly close to the sea and
frequents the sandy shores of Cette, Palavas and the Golfe Juan;
lastly, S. laticollis, who is much more widely distributed than either
of the others and is found up the Rhone Valley at least as far as
Lyons. In addition, I have studied an African species, S. cicatricosus,
picked up near Constantine. Well, in all four species, the absence of
tarsi on the front legs has been an invariable fact, with not a single
exception, at any rate within the range of my observations. The Scarab
therefore is maimed from the start; and it is a natural peculiarity in
his case, not an accident.
Besides, there is another argument in support of this statement. If the
lack of fore-fingers were an accidental mutilation, due to violent
exertion, there are other insects, Dung-beetles too, who habitually
undertake works of excavation even more arduous than the Scarab’s, and
who ought therefore, a fortiori, to be deprived of their front tarsi,
since these are useless and even irksome when the leg has to serve as a
powerful digging-implement. The Geotrupes, for instance, who so well
deserve their name, meaning Earth-piercers, sink wells in the hard soil
of the roads, among stones cemented with clay: perpendicular wells so
deep that, to inspect the cell at the bottom of them, we have to make
use of a stout spade; and even then we do not always succeed. Now these
unrivalled miners, who easily open up long tunnels in a substance whose
surface the Sacred Beetle would hardly be able to disturb, have their
front tarsi intact, as if cutting through rocks were work calling for
delicate tools rather than strong ones. Everything then supports the
belief that, if we could see the Scarab while still a novice in his
native cell, we should find him to be mutilated in just the same way as
the much-travelled veteran who has worn himself out with toil.
This absence of fingers might serve as the foundation for an argument
in favour of the theories now in fashion: the struggle for life and the
evolution of the species. People might say:
‘The Scarabs began by having tarsi to all their legs, in conformity
with the general laws of insect structure. In one way or another, some
of them lost these troublesome appendages to their front legs, they
being hurtful rather than useful. Finding themselves the better for
this mutilation, which made their work easier, they gained the
advantage over their less-favoured fellows; they founded a family by
handing down their fingerless stumps to their descendants; and the
fingered insect of antiquity ended by becoming the maimed insect of our
times.’
I am ready to yield to this reasoning if you will first tell me why,
with similar but much harder tasks to perform, the Geotrupes has
retained his tarsi. Until then we will go on believing that the first
Scarab who rolled his ball, perhaps on the shore of some lake in which
the Palæotherium bathed, was as innocent of front tarsi as his
descendant of to-day.