At the end of April the young grubs imprisoned in my cages, hitherto lying motionless and hidden in the spongy heap of egg-skins, suddenly began to move. They scattered, and ran about in all directions through the boxes and jars in which they have passed the winter. [[165]]Their hurried movements and untiring energy showed they were in search of something, and the natural thing for them to seek was food. For these grubs were hatched at the end of September, and since then, that is to say for seven long months, they had taken no nourishment, although they were by no means in a state of torpor. From the moment of their hatching they are doomed, though full of life, to an absolute fast lasting for seven months; and when I saw their excitement I naturally supposed that an imperious hunger had set them bustling in that fashion.
The food they desired could only be the contents of the Anthophora’s cells, since at a later stage the Sitaris is found in those cells. Now these contents are limited to honey and Bee-grubs.
I offered them some cells containing larvæ: I even slipped the Sitares into the cells, and did all sorts of things to tempt their appetite. My efforts were fruitless. Then I tried honey. In hunting for cells provisioned with honey I lost a good part of the month of May. Having found them I removed the Bee-grub from some of them, and laid the Sitaris-grub on the surface of the honey. Never did experiment break down so completely! Far from eating the honey, the grubs became entangled in the sticky mass and perished in it, suffocated. “I have offered you larvæ, cells, [[166]]honey!” I cried in despair. “Then what do you want, you fiendish little creatures?”
Well, in the end I found out what they wanted. They wanted the Anthophora herself to carry them into the cells!
When April comes, as I said before, the heap of grubs at the entrance to the Bees’ cells begins to show signs of activity. A few days later they are no longer there. Strange as it may appear, they are all careering about the country, sometimes at a great distance, clinging like grim death to the fleece of a Bee!
When the Anthophoræ pass by the entrance to their cells, on their way either in or out, the young Sitaris-grub, who is lying in wait there, attaches himself to one of the Bees. He wriggles into the fur and clutches it so firmly that he need not fear a fall during the long journeys of the insect that carries him. By thus attaching himself to the Bee the Sitaris intends to get himself carried, at the right moment, into a cell supplied with honey.
One might at first sight believe that these adventurous grubs derive food for a time from the Bee’s body. But not at all. The young Sitares, embedded in the fleece, at right angles to the body of the Anthophora, head inwards, tail outwards, do not stir from the spot they have selected, a point near the Bee’s shoulders. [[167]]We do not see them wandering from spot to spot, exploring the Bee’s body, seeking the part where the skin is most delicate, as they would certainly do if they were really feeding on the insect. On the contrary, they are always fixed on the toughest and hardest part of the Bee’s body, a little below the insertion of the wings, or sometimes on the head; and they remain absolutely motionless, clinging to a single hair. It seems to me undeniable that the young Sitares settle on the Bee merely to make her carry them into the cells that she will soon be building.
But in the meantime the future parasites must hold tight to the fleece of their hostess, in spite of her rapid flights among the flowers, in spite of her rubbing against the walls of the galleries when she enters to take shelter, and in spite, above all, of the brushing which she must often give herself with her feet, to dust herself and keep spick and span. We were wondering a little time ago what the dangerous, shifting thing could be on which the grub would have to establish itself. That thing is the hair of a Bee who makes a thousand rapid journeys, now diving into her narrow galleries, now forcing her way down the tight throat of a flower.
We can now quite understand the use of the two spikes, which close together and are able to take hold of hair more easily than the most delicate tweezers. We [[168]]can see the full value of the sticky liquid that helps the tiny creature to hold fast; and we can realise that the elastic probes and bristles on the legs serve to penetrate the Bee’s down and anchor the grub in position. The more one considers this arrangement, which seems so useless as the grub drags itself laboriously over a smooth surface, the more does one marvel at all the machinery which this fragile creature carries about to save it from falling during its adventurous rides.