Fabre's Book of Insects

by Jean-Henri Fabre

In a few cells I found this egg floating all alone on the surface of the honey: in others, very many others, I saw, [[171]]lying on the Bee’s egg as though on a sort of raft, a young Sitaris-grub. Its shape and size were those of the creature when it is hatched. Here, then, was the enemy within the gates.

When and how did it get in? In none of the cells was I able to detect any chink by which it could have entered: they were all sealed quite tightly. The parasite must have established itself in the honey-warehouse before the warehouse was closed. On the other hand, the open cells, full of honey but as yet without an egg, never contain a Sitaris. The grub must therefore gain admittance either while the Bee is laying the egg, or else afterwards, while she is busy plastering up the door. My experiments have convinced me that the Sitaris enters the cell in the very second when the egg is laid on the surface of the honey.

If I take a cell full of honey, with an egg floating in it, and place it in a glass tube with some Sitaris-grubs, they very rarely venture inside it. They cannot reach the raft in safety: the honey that surrounds it is too dangerous. If one of them by chance approaches the honey it tries to escape as soon as it sees the sticky nature of the stuff under its feet. It often ends by falling back into the cell, where it dies of suffocation. It is therefore certain that the grub does not leave the fleece of the Bee [[172]]when the latter is in her cell or near it, in order to make a rush for the honey; for this honey would inevitably cause its death, if it so much as touched the surface.

We must remember that the young Sitaris which is found in a closed cell is always placed on the egg of the Bee. This egg not only serves as a raft for the tiny creature floating on a very treacherous lake, but also provides it with its first meal. To get at this egg, in the centre of the lake of honey, to reach this raft which is also its first food, the young grub must somehow contrive to avoid the fatal touch of the honey.

There is only one way in which this can be done. The clever grub, at the very moment when the Bee is laying her egg, slips off the Bee and on to the egg, and with it reaches the surface of the honey. The egg is too small to hold more than one grub, and that is why we never find more than one Sitaris in a cell. Such a performance on the part of a grub seems extraordinarily inspired—but then the study of insects constantly gives us examples of such inspiration.

When dropping her egg upon the honey, then, the Anthophora at the same time drops into her cell the mortal enemy of her race. She carefully plasters the lid which closes the entrance to the cell, and all is done. A second cell is built beside it, probably to suffer the same fate; and so on until all the parasites sheltered by [[173]]her fleece are comfortably housed. Let us leave the unhappy mother to continue her fruitless task, and turn our attention to the young larva which has so cleverly secured for itself board and lodging.

Let us suppose that we remove the lid from a cell in which the egg, recently laid, supports a Sitaris-grub. The egg is intact and in perfect condition. But now the work of destruction begins. The grub, a tiny black speck which we see running over the white surface of the egg, at last stops and balances itself firmly on its six legs; then, seizing the delicate skin of the egg with the sharp hooks of its mandibles, it tugs at it violently till it breaks and spills the contents. These contents the grub eagerly drinks up. Thus the first stroke of the parasite’s mandibles is aimed at the destruction of the Bee’s egg.

This is a very wise precaution on the part of the Sitaris-grub! It will have to feed on the honey in the cell: the Bee’s grub which would come out of the egg would also require the honey: there is not enough for two. So—quick!—a bite at the egg, and the difficulty is removed.

Moreover, another reason for the destruction of the egg is that special tastes compel the young Sitaris to make its first meals of it. The tiny creature begins by greedily drinking the juices which the torn wrapper of [[174]]the egg allows to escape. For several days it continues to rip the envelope gradually open, and to feed on the liquid that trickles from it. Meanwhile it never touches the honey that surrounds it. The Bee’s egg is absolutely necessary to the Sitaris-grub, not merely as a boat, but also as nourishment.

At the end of a week the egg is nothing but a dry skin. The first meal is finished. The Sitaris-grub, which is now twice as large as before, splits open along the back, and through this slit the second form of this singular Beetle falls on the surface of the honey. Its cast skin remains on the raft, and will presently disappear with it beneath the waves of honey.