SAPRINI, DERMESTES AND OTHERS

Twenty thousand, Réaumur1 tells us, twenty thousand embryos in the body of the Grey Flesh-fly!2 Twenty thousand! What does she want with this formidable family? With offspring that reproduce themselves several times in a year, does she intend to dominate the world? She would be capable of it. Speaking of the Bluebottle,3 who is far less prolific, Linnæus4 already wrote:

“Three Flies consume the carcase of a Horse as quickly as a Lion could do it.”

What could not the other accomplish?

Réaumur reassures us:

“Despite such amazing fertility,” he says, “these sorts of Flies are not commoner than others which resemble them and in whose ovaries we find only two eggs. The maggots of the former are seemingly destined to feed other insects, which very few of them escape.”

Now which are the insects charged with this task of extirpation? The master suspects their existence; he guesses that they are there, without having had the occasion to observe them. My retting-vats provide me with the means of filling up this historical gap; they show me the consumers at their appointed task of thinning out the obtrusive maggot. Let me record this tragic business.

A larger Adder is liquefying, thanks to the solvent dribbled by the teeming vermin. The earthenware dish becomes a porringer full of cadaveric fluid whence the reptile’s backbone emerges spiral-wise. The scaly sheath swells up and throbs in gentle undulations, as though an internal tide were lifting the skin with its ebb and flow. Gangs of workers pass to and fro between skin and muscle, seeking a suitable spot for their activities. A few of them show themselves for a moment between the disjointed scales. Surprised by the light, they dart forth their pointed heads and at once pop in again. Close beside them, in the gaps between the spiral coils, the highly-flavoured broth lies in stagnant channels. Here the greater part are feeding in shoals, motionless, packed together, with their bud-shaped breathing-holes expanded on the surface of the liquid. Their numbers are indefinite and immense, defying computation.

Many strangers take part in the maggots’ banquet. The first to hasten to it are the Saprini, lovers of corruption, as their name implies. They arrive at the same time as the Luciliæ,5 before the flesh liquefies. They take up their positions, inspect the body, tease one another in the sunshine, disappear under the corpse. The time has not yet come for a good square meal. They wait.

Despite their habit of dwelling in fetid surroundings, the Saprini are pretty insects. Well-armoured, thickset, moving by fits and starts with short, quick steps, they glisten like beads of jet. On their shoulders are chevron-like stripes which the classifier notes to mark where he stands in the midst of this specific variety; they temper the brilliance of their black wing-cases with stippled spaces which diffuse the light. Some display polished, shimmering patches on a dull-bronze background chased as though with the graver’s tool. Sometimes the sombre ebony costume is embellished with brightly-coloured ornaments. The Spotted Saprinus decorates each wing-case with a splendid orange crescent. In short, considered merely from the æsthetic point of view, these little undertakers’ assistants are by no means devoid of merit. They cut an excellent figure in the glass cases of our collections.

But one should see them above all at work. The Snake is submerged in the broth of its liquefied flesh. The maggots are legion. With their diadem-like valves gently opening and closing, they lie, spread like a field of flowers on the pool of meat-extract. The hour has come for the Saprini to begin feasting.

Busily bustling to and fro on the parts that are still uncovered, they scale the reefs and promontories formed by the reptile’s coils and from these points, protected against the perilous flood, they fish for their favourite titbit. Here is a grub near the bank, one not too large and for that reason all the more tender. One of the gluttons sees it, cautiously approaches the depths, snaps with his mandibles and pulls, uprooting his prey. The plump little sausage emerges, wriggling. As soon as it is on dry land, the victim is disembowelled and rapturously crunched up. Not a scrap is left. The morsel is often shared, two collaborators tugging in opposite directions, but without a scuffle.

Maggot-fishing is carried on in this way at every point of the shore. The catch is not abundant, for most of the fry are some distance from the mainland, in deep waters where the Saprini do not venture. They never risk wetting their feet. However, the tide withdraws by degrees, absorbed by the sand and evaporated by the sun. The grubs retreat under the corpse; the Saprini follow them. The massacre becomes general. A few days later, we remove the Snake. There are no maggots left. Nor are there any in the sand, making ready for the metamorphosis. The horde has disappeared: it has been eaten.

The extermination is so complete that, to obtain pupæ, I have to resort to rearing them in private, guarding the larvæ against the invasion of the Saprini. The earthenware pans in the open air, though thoroughly searched, never yield me any, however numerous the maggots were at the outset. During my earlier experiments, when as yet I had no suspicion of the massacre, I could not get over my surprise when, after noting an abundance of vermin under this or that piece of carrion a few days before, I no longer found anything, even in the sand. I should have concluded that the occupants had migrated in a body, had it been permissible to imagine a maggot making a long journey through a waterless world.

The Saprini, those lovers of fat sausages are entrusted with the task of thinning out the Grey Fly, of whose twenty thousand offspring only a few will survive, just enough to maintain the race within proper limits. They flock about the dead Mole or Adder; but, kept at a distance by the too liquid sanies and, for that matter, able to live on a few frugal mouthfuls, they wait until the maggots’ work is finished. Then, the liquefaction of the corpse completed, they slaughter the liquidators. To purge the soil swiftly of life’s offal, the scavenging maggot multiplies its legions; then, having itself become a peril by reason of its numbers, it disappears, exterminated, when its cleansing task is done.

In my district, I obtain nine species of Saprini, some found under carrion, others under dung. I give their names in a footnote.6 The first four species hasten to my earthenware pans, but the most numerous and most assiduous, those on whom the bulk of the work falls, are S. subnitidus and S. detersus. They arrive as early as April, at the same time as the Luciliæ, whose offspring they ravage with the same zeal as that of the Grey Fly. Both of them abound in my charnel-pits until the torrid sun of the dog-days puts an end to the invasion of the Flies by drying up the exposed carrion too quickly. They reappear in September, with the first cool breezes of autumn.

Flesh or fish, fur, feather or reptile, everything suits them because it also attracts the maggot, their favourite meat. While waiting for the vermin to grow, they take a few sips of the sanies; but these are scarcely more than an appetizer in preparation for the great feast, when the wriggling grubs are fattened to a turn.

Seeing them so active, one at first pictures them as occupied with family-cares. So I believed; and I was wrong. Under the carrion in my necrotic laboratory, there is never an egg belonging to them, never a larva. The family must be established elsewhere, in the dung-hills and dust-heaps apparently. I have, in fact, found their nymphs, which are easily recognized, in March, on the floor of a poultry-run saturated with the droppings of the fowls. The adults visit my retting-pans to feast upon the maggot. When their mission is accomplished, in the late autumn, they seem to return to the filth under whose shelter the generation is prepared which, as soon as winter is over, hastens to the dead bodies of animals to moderate the excesses of the Sarcophagæ7 and the Luciliæ.

The labours of the Fly do not satisfy the requirements of hygiene. When the soil has drunk the cadaveric extract elaborated by the grubs, a great deal remains that cannot be liquefied or dried up by the heat. Other workers are needed, who treat the mummified carcase anew, nibbling at the shrivelled muscles and tendons until the relics are reduced to a heap of bones as clean as ivory.

The Dermestes are charged with this long labour of gnawing. Two species come to my earthenware pans at the same time as the Saprini: D. undulatus, Brahm., and D. Frischii, Kugel. The first, striped with fine, snow-white, wavy lines on a black ground, has a red corselet speckled with brown spots; the second, the larger of the two, is dull black all over, with the sides of the corselet powdered ashen grey. Both wear white flannel underneath, which forms a violent contrast with the rest of the costume and seems inconsistent with the insect’s calling.

The Necrophorus,8 the burier of the dead, has already shown us this propensity for soft stuffs and the clash of discordant colours. He covers his breast with a waistcoat of nankeen flannel, decorates his wing-cases with red stripes and sports an orange club at the tip of his antennæ. The Wavy Dermestes, wearing a leopard-skin cape and a jerkin striped with ermine, could almost, humble though he be, rival the elegance of this mighty undertaker.

Both of them numerous, the two Dermestes come to my earthenware receptacles with a common aim; to dissect the dead body to the bone and to feed on what the maggots have left. If the work of these is not completed, if the lower surface of the corpse is still oozing, they wait, gathered on the edges of the pan or clinging in long rows to the cords by which it is slung. In their tumultuous impatience, falls are frequent, which throw the clumsy insect on its back and for a moment reveal the white flannel of the belly. The thoughtless Beetle soon recovers his feet, runs away and once more climbs the strings. In the kindly sunshine, frequent pairings occur, which is another way of killing time. There are no fights for the best places and the best morsels. The banquet is plentiful; there is room for all.

At last the victuals are in the requisite condition; the maggots have disappeared, carried off by the Saprini; these last are themselves becoming scarce and are repairing elsewhither in search of another hoard of vermin. The Dermestes take possession of the corpse and remain indefinitely, even during the cruel dog-days, when the excessive heat and drought have put all else to flight. Under cover of the dried-up carcase, in the shadow of the Mole’s fur, which makes an impenetrable screen, they nibble and gnaw and clip as long as a scrap of edible matter remains on the bones.

And the work of consuming goes fast, for one of the Beetles, Frisch’s Dermestes, is surrounded by her family, who are endowed with the same appetites. Parents and larval offspring of all ages feast higgledy-piggledy, insatiably. As for the Wavy Dermestes, the other’s collaborator in the dissection of corpses, I do not know where she lays her eggs. My pans have taught me nothing in this respect. As against that, they tell me a great deal about the larva of the other Dermestes.

All through the spring and the greater part of the summer the adult abounds beneath my carcases, accompanied by the youngsters, ugly creatures covered with wild bristle of dark hairs. The pitch-black back has a red stripe running down the middle from end to end. The white-leaded lower surface already promises the white flannel of maturity. The penultimate segment is armed, above, with two curved points. These are grapnels, which enable the grub to slip swiftly through the interstices of the bones.

The exploited carcase seems deserted, so quiet is everything outside. Lift it up. Instantly what liveliness, what confusion! Surprised by the sudden rush of light, the hairy-backed larvæ dive under the remains, wriggling their way into the crevices of the skeleton; the adults, whose movements are less supple, run to and fro in their distress, burying themselves as best they can, or flying off. Leave them to their darkness: they will resume the interrupted work and, some time in July, we shall find their nymphs with no other shelter than the remnants of the corpse.

Although the Dermestes disdains to burrow underground in order to undergo their transformation, finding sufficient protection beneath the remains of the wasted corpse, this is by no means the case with the Silpha, another exploiter of the dead. Two species visit my pans: S. rugosa, Linn., and S. sinuata, Fab. Although assiduously frequented by both species, my appliances tell me nothing definite about the history of these two habitual associates of the Dermestes and the Saprinus. Perhaps I took up the matter too late.

At the end of the winter, indeed, I find beneath a toad the family of the Wrinkled Silpha. It consists of some thirty naked larvæ, glossy, black, flat and tapering to a point. The abdominal segments end on either side in a spike aimed backwards. The penultimate segment has short, bristling filaments. Hidden in the shadow of the disembowelled toad, these larvæ are nibbling the dry meat, long toasted in the sun.

About the first week in May, they repair underground, where each of them digs itself a spherical recess. The nymphs are continually on the alert. At the slightest disturbance, they twirl their pointed abdomen, brandishing it to and fro with a rapid whirling motion. At the end of the same month, the adults leave the soil. Equally precocious, it would seem, are the insects that come to my pans, to eat their fill but not to reproduce their species. Family cares are postponed to a later season, to the end of autumn.

I shall mention but briefly the Necrophorus (N. vestigator, Herch.), whose feats I have described elsewhere.9 He comes to my apparatus, of course, but without making a long stay, the carcases being as a rule too large for his burying-methods. For that matter, I myself would thwart his enterprises if it did suit him. I want to see not burials but operations in the open air. If the sexton is persistent, I dissuade him by pestering him.

Let us pass on to others. Who is this, assiduous visitor, but appearing only in small parties, hardly more than four or five at a time? It is an Hemipteron,10 a slender Bug, with red wings and with stout, toothed thighs to its hind-legs; it is the Spurred Alydus (A. calcaratus, Linn.), a near kinswoman of the Reduvius, so interesting because of her explosive egg.11 She too has an appetite for game, but how moderate compared with the other’s! I see her wandering over my specimens in search of a denuded bone bleached by the sun. After finding a suitable point she applies the tip of her rostrum to it and for some time remains motionless.

With her rigid implement, fine as a horse-hair, what can she extract from that bone? I ask myself in vain, so dry does the surface exploited appear to be. Perhaps she collects the vestiges of grease left by the Dermestes’ conscientious tooth. Quite a secondary worker, she gleans where others have reaped. I should have liked to follow this bone-sucker’s habits more closely and above all to obtain her eggs, in the hope of discovering some little mechanical secret at the moment of hatching. My attempts failed. When imprisoned in a glass jar with the victuals which she requires, the Alydus allows herself to pine away from one day to the next. She needs to fly in freedom over the neighbouring rosemary-bushes, after her sojourn in the retting-vats.

We will close this list of undertakers’ assistants with the Staphylini,12 the tribe with the short wing-cases. Two species, both inmates of dung-hills, haunt my earthenware pans: Aleochara fuscipes, Fab., and Staphylinus maxillosus, Linn. My attention is drawn rather to the latter, the family giantess.

Barred with ash-grey velvet on a black ground, the Big-jawed Staphylinus reaches me only in small numbers, always one by one. She flies up hastily, perhaps from the stables hard by. She alights, coils her belly, opens her pincers and dives impetuously into the Mole’s fur. Then, with her powerful nippers, she punctures the skin, now blue and distended by gases. The sanies oozes out. The glutton greedily eats her fill; and that is all. Soon she departs, as suddenly as she came.

I have not had the good fortune to see anything further. The big Staphylinus hastens to my pans only to feast upon a highly seasoned dish. Her family dwelling must be in the dung-hills about the stables of the neighbourhood. I should have much liked to see her make her home in my charnel-pits.

The Staphylinus is a curious creature indeed. Her short wing-cases, covering just the top of her shoulders, her fierce mandibles, overlapping like a meat-hook, and her long, naked abdomen, which she lifts and brandishes in the air, make her a being apart, of alarming aspect. I should like to learn something of her larva. As I cannot do this with the Beetle that visits my Moles, I apply myself to a kindred species, as nearly as possible her equivalent in respect of size.

In winter, when I raise the stones beside the foot-paths, I often come across the larva of the Stinking Staphylinus (S. olens, Müll.), or Devil’s Coach-horse. The ugly animal, which is not very different in shape from the adult, measures about an inch in length. The head and thorax are a fine, glossy black; the abdomen is brown and bristles with sparse hairs. The cranium is flat; the mandibles are black and very sharp, opening in a ferocious crescent whose width is more than twice the diameter of the head. The mere sight of these curved daggers enables us to guess the highwayman’s habits.

The creature’s most singular implement is the end of the intestine, which is covered with a horny substance prolonged into a stiff tube standing at right angles to the axis of the body. This member is an instrument of locomotion, an anal crutch. In walking, the animal presses the tip of this crutch to the ground and thrusts backwards as with a lever, while the legs struggle forward. Doré,13 the famous illustrator of extravagant notions, conceived a similar system. He shows us somewhere a legless cripple seated in a bowl supported by a pivot and working himself along on his hands. The artist’s grotesque imagination might well have been inspired by the grotesque appearance of the insect.

Even among its own kind, the crutched insect is a bad neighbour. Very rarely do I find two larvæ under the same stone; and, when this happens, one of the two is always in a pitiful state: the other is devouring it as if it were its ordinary game. Let us watch this conflict of two cannibals, each thirsting for the other’s blood.

In the arena furnished by a tumbler containing some moist sand, I place two larvæ of equal strength. The moment they face each other, they suddenly rear up, bending their bodies backwards, with the six legs in the air, hooks of the mandibles wide open and the anal crutch firmly fixed. They look magnificently audacious in this posture of attack and defence. This above all is the best moment for recognizing the great advantage of the pivot at the tail. Though in danger of being disembowelled by its adversary, the larva has no other support than the tip of the abdomen and the terminal tube. The six legs play no part in sustaining it; they wave in the air, all six free and ready to clasp the enemy.

The two adversaries are standing face to face. Which of the two will eat the other? Chance decides. Mutual threats are followed by a hand-to-hand struggle. The fight does not last long. Favoured by the hazards of the fray, or perhaps timing its blows more accurately, one seizes the other by the scruff of the neck. It is done: any resistance on the part of the vanquished is impossible; blood flows and murder has been committed. When all movement has ceased, the victor devours the slain, leaving only the unpleasantly hard skin.

Is this frenzy for killing among creatures of the same species due to cannibalism enforced by starvation? I really do not think so. When well-fed to begin with, rich, moreover, in the victuals which I lavish upon them, these miscreants are as prone as ever to butcher their kith and kin. In vain I overwhelm them with choice morsels: succulent sausages in the shape of young Anoxia-larvæ;14 Vitrinæ,15 tiny molluscs which I give them half-crushed, to spare the banqueters the trouble of extracting them from the shell. As soon as they are confronted, the two bandits, which have just been feasting on a prey as bulky as themselves, stand up, challenging each other and snapping at each other until one of the two is dead. Then follows the odious meal. To eat the murdered kinsman is, it seems, the usual thing.

The Mantis16 who, in captivity, preys upon her mates has the madness of the rutting beast as her excuse. The fierce, jealous creature can find no better way of getting rid of her rivals than to eat them, provided she be the stronger. This procreative depravity is found much higher in the scale. The Cat and the Rabbit notably are prone to devour the young family which might stand in the way of their unslaked passions.

In my glass jars and under the flat stones in the fields the Devil’s Coach-horse has no such excuse. Thanks to its larval state, it is utterly indifferent to the disorders attendant on the pairing. Those of its fellows which it encounters are not its amorous rivals. And yet without more ado they seize and slay one another. A fight to the death decides which is to be the consumed and which the consumer.

In our language we have the word anthropophagi to denote the horrible eating of man by man; we have nothing to express a similar act in animals of the same species. A proverbial phrase would even seem to say that such a term is uncalled for, except where man is concerned, that baffling admixture of nobility and baseness. Wolf does not eat Wolf, says the wisdom of the nations. Well, here we have the larva of the Stinking Staphylinus giving the lie to the proverb.

What a morality. In this connection, I should have wished to consult the Big-jawed Staphylinus when she came to visit my highly-seasoned Moles, my putrefying Snakes. But she always refused to divulge her secrets, withdrawing from the charnel-pit once she had filled her maw.