The grasshoppers taken from the nests, five in number, were in all cases alive, there being a quivering of the mouth parts, and in some cases of the legs also, without any stimulation. This condition lasted for twenty-four hours from the time the poison was injected. After that they became quiet, but remained alive until they were destroyed by the larvæ.
NEST OF TACHYTES
It is a curious thing that in these wasps is found the perfection of that method of paralyzing the prey which is so much dwelt upon by Fabre, although from their habits this fine workmanship is not of the slightest use to them. They entomb their victims underground, where the conditions are favorable to their preservation, and the extremely short period that elapses between the laying of the egg and the spinning of the cocoon makes it a matter of indifference whether the grasshopper is alive or dead, since in any case it would be eaten before decomposition set in.
We deserve no credit for discovering a second species, Tachytes peptonica, for by her loud buzzing, slow flight, and persistent hovering over the nest she gave us every assistance in her power. She looks and acts like one of the large leaf-cutting bees, and this resemblance is heightened by the fact that the grasshopper which she carries is frequently of a leaf-green color. Her nest, which is sometimes on the bare ground and sometimes in the grass, has no external sign to mark it, and when with a great deal of fuss and buzzing she descends and burrows, it closes behind her and disappears from view, so that unless one marks the exact spot there is no way of detecting it afterward. On her exit a very slight amount of scratching closes the hole and leaves it looking exactly like the surrounding surface; so that in comparing her work with the protracted labor of Ammophila and some species of Pompilus in disguising the locality of the nest, we were struck by the success to which she attained with a very trifling amount of effort.
It takes peptonica thirty or forty minutes to catch a grasshopper, and at each visit she remains for ten or fifteen minutes inside the nest. The grasshopper is carried in the mandibles, supported by the second and third pairs of legs. We never succeeded in opening a nest of this species, but a grasshopper taken as the wasp was bringing it home did not die until the sixth day.
In our summer work we often found ourselves wishing that we could be in half a dozen places at once and could chase several wasps at the same time. Never did we feel these desires more keenly than on the twenty-ninth of July, when, after spending the best part of an hour in watching the hunting of an Ammophila, we were obliged to choose between following her to a possible conclusion, and giving our attention to a little jet-black wasp, Lyroda subita, which we now saw for the first time. This wasp was running around a bunch of clover in a nervous, agitated manner, as though she were oppressed by some great anxiety. The chance of discovering something entirely new decided us to relinquish our Ammophiline hopes, and we sat down at the feet of our new teacher.
We could not see anything remarkable about that bunch of clover, but certainly the spot had some strong attraction for the uneasy little wasp. She ran off first in one direction and then in another. She circled about and made short flights now this way and now that, but always returned. At last she betrayed the secret of her interest by descending to the ground and picking up a small black cricket which had been lying close by all the time. She flew up into the air with it, but even now did not leave the neighborhood, continuing to fly about from place to place, alighting now and again on the bean plants.