CHAPTER IX
THE MANTIS: HER HATCHING
The eggs of the Praying Mantis usually hatch in bright sunshine, at about ten o’clock on a mid-June morning. The median band or exit-zone is the only portion of the nest that affords an outlet to the youngsters.
From under each scale of that zone we see slowly appearing a blunt, transparent protuberance, followed by two large black specks, which are the eyes. Softly the new-born grub slips under the thin plate and half-releases itself. Is it the little Mantis in his larval form, so nearly allied to that of the adult? Not yet. It is a transition organism. The head is opalescent, blunt, swollen, with palpitations caused by the flow of the blood. The rest is tinted reddish-yellow. It is quite easy to distinguish, under a general overall, the large black eyes clouded by the veil that covers them, the mouth-parts flattened against the chest, the legs plastered to the [[171]]body from front to back. Altogether, with the exception of the very obvious legs, the whole thing, with its big blunt head, its eyes, its delicate abdominal segmentation and its boatlike shape, reminds us somewhat of the first state of the Cicadæ on leaving the egg, a state which is pictured exactly by a tiny, finless fish.
Here then is a second instance of an organization of very brief duration having as its function to bring into the light of day, through narrow and difficult passes, a microscopic creature whose limbs, if free, would, because of their length, be an insurmountable impediment. To enable him to emerge from the exiguous tunnel of his twig, a tunnel bristling with woody fibres and blocked with shells already empty, the Cicada is born swathed in bands and endowed with a boat shape, which is eminently suited to slipping easily through an awkward passage. The young Mantis is exposed to similar difficulties. He has to emerge from the depths of the nest through narrow, winding ways, in which full-spread, slender limbs would not be able to find room. The high stilts, the murderous harpoons, the delicate antennæ, organs which will be most useful presently, in [[172]]the brushwood, would now hinder the emergence, would make it very laborious, impossible. The creature therefore comes into existence swaddled and furthermore takes the shape of a boat.
The case of the Cicada and the Mantis opens up a new vein to us in the inexhaustible entomological mine. I extract from it a law which other and similar facts, picked up more or less everywhere, will certainly not fail to confirm. The true larva is not always the direct product of the egg. When the newborn grub is likely to experience special difficulties in effecting its deliverance, an accessory organism, which I shall continue to call the primary larva, precedes the genuine larval state and has as its function to bring to the light of day the tiny creature which is incapable of releasing itself.
To go on with our story, the primary larvæ show themselves under the thin plates of the exit-zone. A vigorous flow of humours occurs in the head, swelling it out and converting it into a diaphanous and ever-throbbing blister. In this way the splitting-apparatus is prepared. At the same time, the little creature, half-caught under its scale, sways, pushes forward, draws back. Each [[173]]swaying is accompanied by an increase of the swelling in the head. At last the prothorax arches and the head is bent low towards the chest. The tunic bursts across the prothorax. The little animal tugs, wriggles, sways, bends and straightens itself again. The legs are drawn from their sheaths; the antennæ, two long parallel threads, are likewise released. The creature is now fastened to the nest only by a worn-out cord. A few shakes complete the deliverance.
We here have the insect in its genuine larval form. All that remains behind is a sort of irregular cord, a shapeless clout which the least breath blows about like a flimsy bit of fluff. It is the exit-tunic violently shed and reduced to a mere rag.
For all my watchfulness, I missed the moment of hatching in the case of the Grey Mantis. The little that I know is reduced to this: at the end of the spur or promontory with which the nest finishes in front is a small, dull-white speck, formed of very powdery foam. This round pore is only just plugged with a frothy stopper and constitutes the sole outlet from the nest, which is thoroughly strengthened at every other part. It takes [[174]]the place of the long band of scales through which the Praying Mantis is released. It is here that the youngsters must emerge one by one from their casket. Chance does not favour me and I do not witness the exodus, but, soon after the family has come forth, I see dangling at the entrance to the liberating pore a shapeless bunch of white cast-off clothes, thin skins which a puff of wind would disperse. These are the garments flung aside by the young as they make their appearance in the open air; and they testify to the presence of a transition wrapper which permits of movement inside the maze of the nest. The Grey Mantis therefore also has her primary larva, which packs itself up in a narrow sheath, conducive to escape. The period of this emergence is June.