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 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; [31] 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 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