We will return to the Sphex, with whose burrow we must make ourselves acquainted before we go further. This burrow is a hole made in fine sand, or rather in a sort of dust at the bottom of a natural shelter. Its entrance-passage is very short, merely an inch or two, without a bend, and leads to a single, roomy, oval chamber. The whole thing is a rough den, hastily dug out, rather than a leisurely and artistically excavated dwelling. I have explained that the reason for this simplicity is that the game is captured first and set down for a moment on the hunting-field while the Wasp hurriedly makes a burrow in the vicinity, a method of procedure which allows of but one chamber or cell to each retreat. For who can tell whither the chances of the day will lead the huntress for her second capture? The prisoner is heavy and the burrow must therefore be [[179]]near; so to-day’s home, which is too far away for the next Ephippiger to be conveyed to it, cannot be utilized to-morrow. Thus, as each prey is caught, there is a fresh excavation, a fresh burrow, with its single chamber, now here, now there. Having said this, we will try a few experiments to see how the insect behaves when we create circumstances new to it.
Experiment I
A Sphex, dragging her prey along, is a few inches from the burrow. Without disturbing her, I cut with a pair of scissors the Ephippiger’s antennæ, which the Wasp, as we know, uses for harness-ropes. On recovering from the surprise caused by the sudden lightening of her load, the Sphex goes back to her victim and, without hesitation, now seizes the root of the antenna, the short stump left by the scissors. It is very short indeed, hardly a millimetre;[1] no matter: it is enough for the Sphex, who grips this fag-end of a rope and resumes her hauling. With the greatest precaution, so as not to injure the Wasp, I now cut the two antennary stumps level with the skull. Finding nothing left to catch hold of at the familiar points, the insect seizes, close by, one of the [[180]]victim’s long palpi and continues its hauling-work, without appearing at all perturbed by this change in the harness. I leave it alone. The prey is brought home and placed so that its head faces the entrance to the burrow; and the Wasp goes in by herself, to make a brief inspection of the inside of the cell before proceeding to warehouse the provisions. Her behaviour reminds us of that of the Yellow-winged Sphex in similar circumstances. I take advantage of this short moment to seize the abandoned prey, remove all its palpi and place it a little farther off, about half a yard from the burrow. The Sphex reappears and goes straight to her captive, whom she has seen from her threshold. She looks at the top of the head, she looks underneath, on either side, and finds nothing to take hold of. A desperate attempt is made: the Wasp, opening wide her mandibles, tries to grab the Ephippiger by the head; but the pincers have not a sufficient compass to take in so large a bulk and they slip off the round, polished skull. She makes several fresh endeavours, each time without result. She is at length convinced of the uselessness of her efforts. She draws back a little to one side and appears to be renouncing further attempts. One would say that she was discouraged; at least, she smooths her wings with her hind-legs, [[181]]while with her front tarsi, which she first puts into her mouth, she washes her eyes. This, so it has always seemed to me, is a sign in Hymenoptera of giving up a job.
Nevertheless there is no lack of parts by which the Ephippiger might be seized and dragged along as easily as by the antennæ and the palpi. There are the six legs, there is the ovipositor: all organs slender enough to be gripped boldly and to serve as hauling-ropes. I agree that the easiest way to effect the storing is to introduce the prey head first, drawn down by the antennæ; but it would enter almost as readily if drawn by a leg, especially one of the front legs, for the orifice is wide and the passage short or sometimes even non-existent. Then how is it that the Sphex did not once try to seize one of the six tarsi or the tip of the ovipositor, whereas she attempted the impossible, the absurd, in striving to grip, with her much too short mandibles, the huge skull of her prey? Can it be that the idea did not occur to her? Then we will try to suggest it.
I offer her, right under her mandibles, first a leg, next the end of the abdominal rapier. The insect obstinately refuses to bite; my repeated blandishments lead to nothing. A singular huntress, to be embarrassed by her game, not knowing how to seize it by a leg when she is [[182]]not able to take it by the horns! Perhaps my prolonged presence and the unusual events that have just occurred have disturbed her faculties. Then let us leave the Sphex to herself, between her Ephippiger and her burrow; let us give her time to collect herself and, in the calm of solitude, to think out some way of managing her business. I leave her therefore and continue my walk; and, two hours later, I return to the same place. The Sphex is gone, the burrow is still open, and the Ephippiger is lying just where I placed her. Conclusion: the Wasp has tried nothing; she went away, abandoning everything, her home and her game, when, to utilize them both, all that she had to do was to take her prey by one leg. And so this rival of Flourens, who but now was startling us with her cleverness as she dexterously squeezed her victim’s brain to produce lethargy, becomes incredibly helpless in the simplest case outside her usual habits. She, who so well knows how to attack a victim’s thoracic ganglia with her sting and its cervical ganglia with her mandibles; she, who makes such a judicious difference between a poisoned prick annihilating the vital influence of the nerves for ever and a pressure causing only momentary torpor, cannot grip her prey by this part when it is made impossible for her to grip it by any other. To [[183]]understand that she can take a leg instead of an antenna is utterly beyond her powers. She must have the antenna, or some other string attached to the head, such as one of the palpi. If these cords did not exist, her race would perish, for lack of the capacity to solve this trivial problem.
Experiment II
The Wasp is engaged in closing her burrow, where the prey has been stored and the egg laid upon it. With her front tarsi she brushes her doorstep, working backwards and sweeping into the entrance a stream of dust which passes under her belly and spurts behind in a parabolic spray as continuous as a liquid spray, so nimble is the sweeper in her actions. From time to time the Sphex picks out with her mandibles a few grains of sand, so many solid blocks which she inserts one by one into the mass of dust, causing it all to cake together by beating and compressing it with her forehead and mandibles. Walled up by this masonry, the entrance-door soon disappears from sight.
I intervene in the middle of the work. Pushing the Sphex aside, I carefully clear the short gallery with the blade of a knife, take away the materials that close it and restore full [[184]]communication between the cell and the outside. Then, with my forceps, without damaging the edifice, I take the Ephippiger from the cell, where she lies with her head at the back and her ovipositor towards the entrance. The Wasp’s egg is on the victim’s breast, at the usual place, the root of one of the hinder thighs: a proof that the Sphex was giving the finishing touch to the burrow, with the intention of never returning.