THE ONTHOPHAGI
After the notabilities of the Dung-beetle tribe, there remain, in the
very limited radius of my research, the small fry of the Onthophagi, of
whom I could gather a dozen different species around my house. What
will these little ones teach us?
Even more zealous than their larger comrades, they are the first to
hasten to the exploiting of the heap left by the passing mule. They
come up in crowds and stay long, working under the spread table that
gives them shade and coolness. Turn over the heap with your foot. You
will be surprised at the swarming population whose presence no outward
sign betrayed. The largest are scarce the size of a pea, but many are
much smaller still, are dwarfs, no less busy than the others, no less
eager to crumble the filth whose prompt disappearance the public health
demands.
In works of major interest, there is none like the humble, with their
concerted weakness, for realizing immense strength. Swollen by numbers,
the next to nothing becomes an enormous total.
Hurrying in detachments at the first news of the event, assisted
moreover in their wholesome task by their partners, the Aphodians, who
are as weak as they, the tiny Onthophagi soon clear the ground of its
dirt. Not that their appetite is equal to the consumption of such
plentiful provisions. What food do those pigmies need? An atom. But
that atom, selected from among the exudations, must be hunted amid the
fragments of the masticated fodder. Hence, an endless division and
subdivision of the lump, reducing it to crumbs which the sun sterilizes
and the wind dispels. As soon as the work is done—and very well
done—the troop of scavengers goes in search of another refuse-yard.
Outside the period of intense cold, which puts a stop to all activity,
they know no dead season.
And do not run away with the idea that this filthy task entails an
inelegant shape and a ragged dress. The insect knows none of our
squalor. In its world, a navvy dons a sumptuous jerkin; an undertaker
decks himself in a triple saffron sash; a wood-cutter works in a velvet
coat. In like manner, the Onthophagus has his own luxury. True, the
costume is always severe: brown and black are the predominant colours,
now dull, now polished as ebony; but, on this background, what details
of sober and graceful ornament! The graver’s work completes the beauty
of the dress. Tiny chasings in parallel grooves, gnarly beads, dainty
rows of knobs, seed-plots of pearly papillæ are distributed in
profusion among nearly all of them. Yes, the little Onthophagi, with
their stunted bodies and their nimble activity, are really pretty to
look at.
And then how original are their frontal decorations! These peace-lovers
delight in the panoply of war, as though they, the inoffensive ones,
thirsted for battle. Many of them crown their heads with threatening
horns. Let us mention that horned one whose story will occupy us more
particularly. I mean Onthophagus Taurus, clad in raven black. He wears
a pair of long horns, gracefully curved and branching to either side.
No pedigree bull, in the Swiss meadows, can match them for curve or
elegance.
The Onthophagus is a very indifferent artist: his nest is a rudimentary
piece of work, hardly fit to be acknowledged. I obtain it in profusion
from the six species which I have brought up in my jars and
flower-pots. Onthophagus Taurus alone provides me with nearly a
hundred; and I find no two precisely alike, as pieces should be that
come from the same mould and the same laboratory.
To this lack of exact similarity, we must add inaccuracy of shape, now
more, now less accentuated. It is easy, however, to recognize among the
bulk the prototype from which the clumsy nest-builder works. It is a
sack shaped like a thimble and standing erect, with the spherical
thimble-end at the bottom and the circular opening at the top.
Sometimes, the insect establishes itself in the central region of my
apparatus, in the heart of the earthy mass; then, the resistance being
the same in every direction, the sack-like shape is pretty accurate.
But, generally, the Onthophagus prefers a solid basis to a dusty
support and builds against the walls of the jar, especially against the
bottom wall. When the support is vertical, the sack is a short cylinder
divided lengthwise, with a smooth, flat surface against the glass and a
rugged convexity every elsewhere. If the support be horizontal, as is
most frequently the case, the cabin is a sort of undefined oval
pastille, flat at the bottom, bulging and vaulted at the top. To the
general inaccuracy of these contorted shapes, ruled by no very definite
pattern, we must add the coarseness of the surfaces, all of which, with
the exception of the parts touching the glass, are covered with a crust
of sand.
The manner of procedure explains this uncouth exterior. As laying-time
draws nigh, the Onthophagus bores a cylindrical pit and descends
underground to a middling depth. Here, working with the shield, the
chine and the fore-legs, which are toothed like a rake, he forces back
and heaps around him the materials which he has moved, so as to obtain
as best he may a nest of suitable size.
The next thing is to cement the crumbling walls of the cavity. The
insect climbs back to the surface by way of its pit; it gathers on its
threshold an armful of mortar taken from the cake whereunder it has
elected to set up house; it goes down again with its burden, which it
spreads and presses upon the sandy wall. Thus it produces a concrete
casing, the flint of which is supplied by the wall itself and the
cement by the produce of the sheep. After a few trips and repeated
strokes of the trowel, the pit is plastered on every side; the walls,
encrusted with grains of sand, are no longer liable to give way.
The cabin is ready: it now wants only a tenant and stores. First, a
large free space is contrived at the bottom: the hatching-chamber, on
whose inner wall the egg is laid. Next comes the gathering of the
provisions intended for the worm, a gathering made with nice
precautions. Lately, when building, the insect worked upon the outside
of the doughy mass and took no notice of the earthy blemishes. Now, it
penetrates to the very centre of the lump, through a gallery that looks
as though it were contrived with a punch. When trying a cheese, the
buyer employs a hollow cylindrical taster, which he drives well in and
pulls out with a sample taken from the middle of the cheese. The
Onthophagus, when collecting for her grub, goes to work as though
equipped with one of these tasters. She bores an exactly round hole
into the piece which she is exploiting; she goes straight to the
middle, where the material, not being exposed to the contact of the
air, has kept more savoury and pliable. Here and here alone are
gathered the armfuls which, gradually stowed away, kneaded and heaped
up to the requisite extent, fill the sack to the top. Finally, a plug
of the same mortar, the sides of which are made partly of sand and
partly of stercoral cement, roughly closes the cell, in such a way that
an outward inspection does not allow one to distinguish front from
back.
To judge the work and its merit, we must open it. A large empty space,
oval in shape, occupies the rear end. This is the birth-chamber, huge
in dimensions compared with its content, the egg fixed on the wall,
sometimes at the bottom of the cell and sometimes on the side. The egg
is a tiny white cylinder, rounded at either end and measuring a
millimetre [18] in length immediately after it is laid. With no other
support than the spot on which the oviduct has planted it, it stands on
its hind-end and projects into space.
A more or less enquiring glance is quite surprised to find so small a
germ contained in so large a box. What does that tiny egg want with all
that space? When carefully examined within, the walls of the chamber
prompt another question. They are coated with a fine greenish pap,
semi-fluid and shiny, the appearance of which does not agree with the
outward or inward aspect of the lump from which the insect has
extracted its materials. A similar lime-wash is observed in the nest
which the Sacred Beetle, the Copris, the Sisyphus, the Geotrupe and
other makers of stercoraceous preserves contrive in the very heart of
the provisions, to receive the egg; but nowhere have I seen it so
plentiful, in proportion, as in the hatching-chamber of the
Onthophagus. Long puzzled by this brothy wash, of which the Sacred
Beetle provided me with the first instance, I began by taking the thing
for a layer of moisture oozing from the bulk of the victuals and
collecting on the surface of the enclosure without other effort than
capillary action. That was the interpretation which I accepted
originally.
I was wrong. The truth is worthy of attention in a very different way.
To-day, better-informed by the Onthophagus, I know that this lime-wash
itself, this semi-fluid cream, is the product of maternal foresight.
What, then, is this lime-wash found in every cell? The answer is
compulsory: it is a produce of the mother, a special gruel, a milk-food
elaborated for the benefit of the new-born grub.
The young Pigeon puts his beak into that of his parents, who, with
convulsive efforts, force down his gullet first a caseous mash secreted
in the crop and next a broth of grains softened by being partially
digested. He is fed upon disgorged foods, which are helpful to the
weaknesses of an inexperienced stomach. The grub of the Onthophagus is
brought up in much the same way, at the start. To assist its first
attempts at swallowing, the mother prepares for it, in her crop, a
light and strengthening cream.
To pass the dainty from mouth to mouth is, in her case, impossible: the
construction of other cells keeps her busy elsewhere. Moreover—and this
is a more serious detail—the laying takes place egg by egg, at very
long intervals, and the hatching is pretty slow: time would fail, had
the family to be brought up in the manner of the Pigeons. Another
method is perforce needed. The childish pap is disgorged all over the
walls of the cabin in such a way that the nursling finds itself
surrounded by an abundance of bread-and-jam, in which the bread, the
food of the sturdy age, is represented by the uncooked material, as
supplied by the sheep, whereas the jam, the mess of the puny age, is
represented by the same material daintily prepared beforehand in the
mother’s stomach. We shall see the babe presently lick first the jam,
all around it, and then stoutly attack the bread. A child among
ourselves would behave no otherwise.
I should have liked to catch the mother in the act of disgorging and
spreading her broth. I was not able to succeed. Things happen in a
narrow retreat, which the eye cannot enter when the pastry-cook is
busy; and also her fluster at being exhibited in broad daylight at once
stops the work.
If direct observation be lacking, at least the appearance of the
material speaks very clearly and tells us that the Onthophagus, here
rivalling the Pigeon, but with a different method, disgorges the first
mouthfuls for her sons. And the same may be said of the other
Dung-beetles skilled in the art of building a hatching-chamber in the
centre of the provisions.
No elsewhere, in the insect order, except among the Apidæ, who prepare
disgorged food in the shape of honey, is this affection present. The
Dung-workers edify us with their morals. Several of them practise
association in couples and found a household; several anticipate the
suckling, the supreme expression of maternal solicitude, by turning
their crop into a nipple. Life has its freaks. It settles amid ordure
the creatures most highly-endowed with family qualities. True, from
there it mounts, with a sudden flight, to the sublimities of the bird.
The little worm is hatched in about a week: a strange and paradoxical
being. On its back, it has an enormous sugar-loaf hump, the weight of
which drags it over and capsizes it each time it tries to stand on its
legs and walk. At every moment, it staggers and falls under the burden
of the hunch.
Unable to keep its hump upright, the grub of the Onthophagus lies down
on its side and licks the cream of its cell all around it. There is
cream everywhere, on the ceiling, on the walls, on the floor. As soon
as one spot is thoroughly bared, the consumer moves on a little with
the help of its well-shaped legs; it capsizes again and starts licking
again. The room is large and plentifully supplied; and the jam-diet
lasts some time.
The fat babies of the Geotrupe, the Copris and the Sacred Beetle finish
at one brief sitting the dainty wherewith their cabined lodge is hung,
a dainty scantily served and just sufficient to stimulate the appetite
and prepare the stomach for a coarser fare; but the Onthophagus grub,
that lean pigmy, has enough to last it for a week and more. The
spacious natal chamber, which is out of all proportion with the size of
the nursling, has permitted this wastefulness.
At last, the real loaf is attacked. In about a month, everything is
consumed, except the wall of the sack. And now the splendid part played
by the hump stands revealed. Glass tubes, prepared in view of events,
allow me to follow the more and more plump and hunch-backed grub at
work. I see it withdraw to one end of the cell, which has become a
crumbling ruin. Here it builds a casket in which the transformation
will take place. Its materials are the digestive residuum, converted
into mortar and heaped up in the hump. The stercoral architect is about
to construct a masterpiece of elegance out of its own ordure, held in
reserve in that receptacle.
I follow its movements under the magnifying-glass. It buckles itself,
closes the circuit of the digestive apparatus, brings the two poles
into contact and, with the end of its mandibles, seizes a pellet of
dung ejaculated at that moment. This pellet, moulded and measured to
perfection, is very neatly gathered. A slight bend of the neck sets the
rubble-stone in place. Others follow, laid one above the other in
minutely regular courses. Giving a tap here and there with its feelers,
the grub makes sure of the stability of the parts, their accurate
binding, their orderly arrangement. It turns round in the centre of the
work as the edifice rises, even as a mason does when building a tower.
Sometimes, the laid stone becomes loose, because the cement has given
way. The worm takes it up again with its mandibles, but, before
replacing it, coats it with an adhesive moisture. It holds it to its
anus, whence trickles, on the moment, almost imperceptibly, a gummy
consolidating extract. The hump supplies the materials; the intestines
give, if necessary, the connecting glue.
In this way, a nice house is produced, ovoid in shape, polished as
stucco within and adorned on the outside with slightly projecting
scales, similar to those on a cedar-cone. Each of these scales is one
of the rubble-stones out of the hump. The casket is not large: a
cherry-stone would about represent its dimensions; but it is so
accurate, so prettily fashioned that it will bear comparison with the
finest products of entomological industry.