I waited a little; five minutes had not passed when my Bembex, coming like an arrow, alighted on the sand near the plant, still holding the prey which I had noticed when she departed at my chasing her, after her vain attempts to find the entrance to her nest; but this time she did not hunt long. She felt about a little to right and left, but soon turned directly toward the entrance to the tunnel, distant scarcely two inches from the place where she had settled. My Bembex had a memory.
A curious thing about these wasps, and one which shows how much common feeling they have, is that they work in waves, all starting off on their hunting expeditions within a few minutes of each other, and returning together after the chase. At one time all the residents seem to be present, digging their nests, carrying in their booty, dashing at each other, and chasing the parasites with a tremendous amount of humming and swooping about. Then suddenly they are all gone. Nothing remains but multitudes of flies, which keep up a giddy dance over the field, and for ten or fifteen minutes the place seems deserted. Then the wasps begin to return, several coming at a time, and as if by magic the whole scene awakens to life. More than half of the wasps bring nothing home with them, and these fall to robbing their more fortunate companions. Those that are carrying flies must pause a moment, burdened as they are, to scratch away the earth at the entrance to the nest. When unmolested they go in very quickly, but it is just at this point that the marauders fall upon them, displaying an amount of persistence and energy in their attacks that, were it properly directed, might easily enable them to secure flies for themselves.
We once saw a wasp that had been fortunate enough, or perhaps unfortunate enough, to catch an immense fly, the wings of which stood out on both sides very conspicuously. This made her an especial mark for her unprincipled relatives. Half a dozen of them chased her about, like chickens pursuing one of their number that has found a worm. She circled and settled, and circled and swooped around for five or six minutes, continually pursued and attacked by the robbers, and quite unable to get into her nest. At last, curious to see what she was carrying, we made her drop her load, and secured it for ourselves. We found it to be a horse fly, quite dead, but showing no marks of violence. It was not wasted, for we afterward fed it to one of our wasp nurslings at home.