THE WHITE-FACED DECTICUS: THE LAYING AND THE HATCHING OF THE EGGS

The White-faced Decticus is an African insect that in France hardly ventures beyond the borders of Provence and Languedoc. She wants the sun that ripens the olives. Can it be that a high temperature acts as a stimulus to her matrimonial eccentricities, or are we to look upon these as family customs, independent of climate? Do things happen under frosty skies just as they do under a burning sun?

I go for my information to another Decticus, the Alpine Analota (A. alpina, Yersin), who inhabits the high ridges of Mont Ventoux,1 which are covered with snow for half the year. Many a time, during my old botanical expeditions, I had noticed the portly insect hopping among the stones from one bit of turf to the next. This time, I do not go in search of it: it reaches me by post. Following my indications, an obliging forester2 climbs up there twice in the first fortnight of August and brings me back the wherewithal to fill a cage comfortably.

In shape and colouring it is a curious specimen of the Grasshopper family. Satin-white underneath, it has the upper part sometimes olive-black, sometimes bright-green or pale-brown. The organs of flight are reduced to mere vestiges. The female has as wing-cases two short white scales, some distance apart; the male shelters under the edge of his corselet two little concave plates, also white, but laid one on top of the other, the left on the right.

These two tiny cupolas, with bow and sounding-board, rather suggest, on a smaller scale, the musical instrument of the Ephippiger, whom the mountain insect resembles to some extent in general appearance.

I do not know what sort of tune cymbals so small as these can produce. I do not remember ever hearing them in their native [233]haunts; and three months’ home breeding gives me no further information in this respect. Though they lead a joyous life, my captives are always dumb.

The exiles do not seem greatly to regret their cold peaks, among the orange poppies and saxifrages of arctic climes. What used they to browse upon up there? The Alpine meadow-grass, Mont-Cenis violets, Allioni’s bell-flower? I do not know. In the absence of Alpine grasses, I give them the common endive from my garden. They accept it without hesitation.

They also accept such Locusts as can offer only a feeble resistance; and the diet alternates between animal and vegetable fare. They even practise cannibalism. If one of my Alpine visitors limps and drags a leg, the others eat him up. So far I have seen nothing striking: these are the usual Grasshopper manners.

The interesting sight is the pairing, which occurs suddenly, without any prelude. The meeting takes place sometimes on the ground, sometimes on the wirework of the cage. In the latter case, the sword-bearer, firmly hooked to the trellis, supports the whole weight of the couple. The other is back [234]downwards, his head pointing to his mate’s tail. With his long, fleshy-shanked hind-legs, he gets a grip of her sides; with his four front legs, often also with his mandibles, he grasps and squeezes the sabre, which projects slantwise. Thus hanging to this sort of greased pole, he operates in space.

When the meeting takes place on the ground, the couple occupy the same position, only the male is lying on his back in the sand. In both cases the result is an opal grain which, in the visible part of it, resembles in shape and size the swollen end of a grape-pip.

As soon as this object is in position, the male decamps at full speed. Can he be in danger? Possibly, to judge from what I have seen. I admit that I have seen it only once.

The bride in this case was grappling with two rivals. One of them, hanging to the sabre, was at work in due form behind; the other, in front, tightly clawed and with his belly ripped open, was waving his limbs in vain protest against the harpy crunching him impassively in small mouthfuls. I had before my eyes, under even more atrocious conditions, the horrors which the Praying Mantis had shown me in the old days: unbridled [235]rut; carnage and voluptuousness in one; a reminiscence perhaps of ancient savagery.

As a rule, the male, a dwarf by comparison with the female, hastens to run away as soon as his task is consummated. The deserted one makes no movement. Then, after waiting twenty minutes or so, she curves herself into a ring and proceeds to enjoy the final banquet. She pulls the sticky raisin-pip into shreds which are chewed with grave appreciation and then gulped down. It takes her more than an hour to swallow the thing. When not a crumb remains, she descends from the wire gauze and mingles with the herd. Her eggs will be laid in a day or two.

The proof is established. The matrimonial habits of the White-faced Decticus are not an exception due to the heat of the climate: the Grasshopper from the cold peaks shares them and surpasses them.

We will return to the big Decticus with the ivory face. The laying follows close upon the strange events which we have described. It is done piecemeal, as the ovaries ripen. Firmly planted on her six legs, the mother bends her abdomen into a semicircle and drives her sabre perpendicularly into the [236]soil, which, consisting in my cages of sifted earth, presents no serious resistance. The ovipositor therefore descends without hesitation and enters up to the hilt, that is to say, to a depth of about an inch.

For nearly fifteen minutes, absolute immobility. This is the time when the eggs are being laid. At last the sabre comes up a little way and the abdomen swings briskly from side to side, communicating an alternate transversal movement to the implement. This tends to scrape out and widen the sunken hole; it also has the effect of releasing from the walls earthy materials which fill up the bottom of the cavity. Thereupon the ovipositor, which is half in and half out, rams down this dust. It comes up a short distance and then dips repeatedly, with a sudden, jerky movement. We should work in the same way with a stick to ram down the earth in a perpendicular hole. Thus alternating the transversal swing of the sabre with the blows of the rammer, the mother covers up the well pretty quickly.

The external traces of the work have still to be done away with. The insect’s legs, which I expected to see brought into play, remain inactive and keep the position [237]adopted for laying the eggs. The sabre alone scratches, sweeps and smooths the ground with its point, very clumsily, it must be admitted.

Now all is in order. The abdomen and the ovipositor are restored to their normal positions. The mother allows herself a moment’s rest and goes to take a turn in the neighbourhood. Soon she comes back to the site where she has already laid her eggs and, very near the original spot, which she recognizes clearly, she drives in her tool afresh. The same proceedings as before are repeated.

Follow another rest, another exploration of the vicinity, another return to the place already sown. For the third time the pointed stake descends, only a very slight distance away from the previous hole. During the brief hour that I am watching her, I see her resume her laying five times, after breaking off to take a little stroll in the neighbourhood; and the points selected are always very close together.

On the following days, at varying intervals, the sowing is renewed for a certain number of times which I am not able to state exactly. In the case of each of these partial [238]layings, the site changes, now here, now there, as this or that spot is deemed the more propitious.

When everything is finished, I examine the little pits in which the Decticus placed her eggs. There are no packets in a foamy sheath, such as the Locust supplies; no cells either. The eggs lie singly, without any protection. I gather three score as the total product of one mother. They are of a pale lilac-grey and are drawn out shuttlewise, in a narrow ellipsoid five or six millimetres long.3

The same isolation marks those of the Grey Decticus, which are black; those of the Vine Ephippiger, which are ashen-grey; and those of the Alpine Analota, which are pale-lilac. The eggs of the Green Grasshopper, which are a very dark olive-brown and, like those of the White-faced Decticus, about sixty in number, are sometimes arranged singly and sometimes stuck together in little clusters.

These different examples show us that the Grasshoppers plant with a dibble. Instead of packing their seeds in little casks of hardened foam, like the Locusts, they put [239]them into the earth one by one or in very small clusters.

The hatching is worth examination; I will explain why presently. I therefore gather plenty of eggs of the big Decticus at the end of August and place them in a small glass jar with a layer of sand. Without undergoing any apparent modification, they spend eight months here under cover, sheltered from the frosts, the showers and the overpowering heat of the sun that would await them under natural conditions.

When June comes, I often meet young Dectici in the fields. Some are already half their adult size, which is evidence of an early appearance dating back to the first fine days of the year. Nevertheless my jar shows no signs of any imminent hatching. I find the eggs just as I gathered them nine months ago, neither wrinkled nor tarnished, wearing, on the contrary, a most healthy look. What causes this indefinitely prolonged delay?

A suspicion occurs to me. The eggs of the Grasshopper tribe are planted in the earth like seeds. They are there exposed, without any kind of protection, to the watery influence of the snow and the rain. Those [240]in my jar have spent two-thirds of the year in a state of comparative dryness. Perhaps, in order to hatch, they lack what grain absolutely needs in order to sprout. Animal seeds as they are, they may yet require under earth the moisture necessary to vegetable seeds. Let us try.

I place at the bottom of some glass tubes, to enable me to make certain observations which I have in mind, a pinch of backward eggs taken from my collection; and on the top I heap lightly a layer of very fine, damp sand. The receptacle is closed with a plug of wet cotton, which will maintain a constant moisture in the interior. The column of sand measures about an inch, which is very much the depth at which the ovipositor places the eggs. Any one seeing my preparations and unacquainted with their object would hardly suspect them of being incubators; he would be more likely to think them the apparatus of a botanist who was experimenting with seeds.

My anticipation was correct. Favoured by the high temperature of the summer solstice, the Grasshopper seed does not take long to sprout. The eggs swell; the front end of each is spotted with two dark dots, [241]the rudiments of the eyes. It is quite evident that the bursting of the shell is near at hand.

I spend a fortnight in keeping a tedious watch at every hour of the day: I have to surprise the young Decticus actually leaving the egg, if I want to solve a question that has long been vexing my mind. The question is this: the Grasshopper’s egg is buried at a varying depth, according to the length of the ovipositor or dibble. An inch is about the most for the seeds of the best-equipped insects in our parts. Now the newborn Decticus, hopping awkwardly in the grass at the approach of summer, is, like the adult, endowed with a pair of very long tentacles, vying with hairs for slenderness; he carries behind him two extraordinary legs, two enormous hinged levers, a pair of jumping-stilts that would be very inconvenient for ordinary walking. How does the feeble little creature set to work, with this cumbrous luggage, to emerge from the earth? By what artifice does it manage to clear a passage through the rough soil? With its antennary plumes, which an atom of sand can break, with its immense shanks, which the least effort is enough to [242]disjoint, the mite is obviously incapable of reaching the surface and freeing itself.

The miner going underground puts on a protective dress. The little Grasshopper also, making a hole in the earth in the opposite direction, must don an overall for emerging from the earth; he must possess a simpler, more compact transition-form, which enables him to come out through the sand, a delivery-shape analogous to that which the Cicada and the Praying Mantis use at the moment of issuing, one from his twig, the other from the labyrinth of his nest.

Reality and logic here agree. The Decticus, in point of fact, does not leave the egg in the form in which I see him, the day after his birth, hopping on the lawn; he possesses a temporary structure better-suited to the difficulties of the emergence. Coloured a delicate flesh-white, the tiny creature is cased in a scabbard which keeps the six legs flattened against the abdomen, stretching backwards, inert. In order to slip more easily under the ground, he has his shanks tied up beside his body. The antennæ, those other irksome appendages, are motionless, pressed against the parcel.

The head is very much bent against the [243]chest. With its big, black ocular specks and its undecided and rather bloated mask, it suggests a diver’s helmet. The neck opens wide at the back and, with a slow throbbing, by turns swells and subsides. That is the motor. The new-born insect moves along with the aid of its occipital hernia. When uninflated, the fore-part pushes back the damp sand a little way and slips into it by digging a tiny pit; then, blown out, it becomes a knob, which moulds itself and finds a support in the depression obtained. Then the rear-end contracts; and this gives a step forward. Each thrust of the locomotive blister means nearly a millimetre4 traversed.

It is pitiful to see this budding flesh, scarcely tinged with pink, knocking with its dropsical neck and ramming the rough soil. The animal glair, not yet quite hardened, struggles painfully with stone; and its efforts are so well directed that, in the space of a morning, a gallery opens, either straight or winding, an inch long and as wide as an average straw. In this way the harassed insect reaches the surface.

Half-caught in its exit-shaft, the disinterred one halts, waits for its strength to [244]return and then for the last time swells its occipital hernia as far as it will go and bursts the sheath that has protected it so far. The creature throws off its miner’s overall.

Here at last is the Decticus in his youthful shape, quite pale still, but darker the next day and a regular blackamoor compared with the adult. As a prelude to the ivory face of a riper age, he sports a narrow white stripe under his hinder thighs.

Little Decticus, hatched before my eyes, life opens for you very harshly! Many of your kindred must die of exhaustion before attaining their freedom. In my tubes I see numbers who, stopped by a grain of sand, succumb half-way and become furred with a sort of silky mildew. The mouldy part soon absorbs their poor little remains. When performed without my assistance, the coming to the light of day must be attended with even greater dangers. The usual soil is coarse and baked by the sun. Without a fall of rain, how do they manage, these immured ones?

More fortunate in my tubes with their sifted and wetted mould, here you are outside, you little white-striped nigger; you bite at the lettuce-leaf which I have given [245]you; you leap about gaily in the cage where I have housed you. It would be easy to rear you, I can see, but it would not give me much fresh information. Let us then part company. I restore you to liberty. In return for what you have taught me, I bestow upon you the grass and the Locusts in the garden.

Thanks to you, I know that Grasshoppers, in order to leave the ground in which the eggs are laid, possess a provisional shape, a primary larval stage, which keeps those too cumbrous parts, the long legs and antennæ, swathed in a common sheath; I know that this sort of mummy, fit only to lengthen and shorten itself a little, has for an organ of locomotion a hernia in the neck, a throbbing blister, an original piece of mechanism which I have never seen used elsewhere as an aid to progression.