NEST OF AGENIA BOMBYCINA
Vespa germanica often cuts off the wings of a dead wasp, or even cuts its body into two parts, before flying away with it, but this is only when the captured insect is too large to be handled in any other way; and Pompilus fuscipennis sometimes cuts off one or more legs from her spider, although without any regular method of procedure.
Agenia bombycina finds a nesting-place to her liking on our smoke-house, in the crevice between the bricks and the wooden door-frame, where she makes clusters of little mud cells, putting one mutilated spider into each, and storing about one a day. Her locality sense is unusually poor, owing apparently to her intense nervousness and excitability, but some individuals are better endowed than others in this respect.[ill245b]
LYCOSA KOCHII, FOUND IN NEST OF AGENIA BOMBYCINA
On a bright morning in the middle of August we stationed ourselves by the smoke-house at eight o’clock, and half an hour later an Agenia began to bring lumps of earth, working out of sight under the door frame. She kept at it steadily, spending three or four minutes in getting a load and one or two in placing it. At twelve o’clock, her nest being ready, she flew away to hunt for a spider. So long as a wasp comes and goes at frequent intervals time slips away rapidly, but to keep one’s attention unflagging through hours of watching is weariness to the flesh. We saw no more of our Agenia until three, when she appeared, half walking, half flying through the grass, going forward. Her spider was held by the spinnerets, and being larger than she was it trailed behind her. On reaching the wall she began to climb; but the weight of the spider made her fall again and again, and forty minutes passed in wearisome toil before it was safely put away. The egg having been laid, she began to bring earth for closing, and we felt thankful that our task as well as hers was nearly over. She worked slowly now, taking ten or fifteen minutes for a trip; but after bringing in the sixth pellet she took on a livelier air, and before long we were convinced that she had begun to build a new cell. For two hours longer we watched her unremitting labor, and when we left her at six o’clock she was flying back and forth as briskly as ever.
Another Agenia, less ambitious, brought her spider at three o’clock and then went to bed in an empty cell, head in, tail sticking out. We cut away a section of the door-frame that covered the spot without disturbing her slumber. This one could never remember where her nest was, but had a long hunt for it every time she brought a pellet; and when she had caught the spider she lost herself completely on the brick wall, going to the very top, and even around the corner on to the side of the building. Every little while she would fly back to the grass at the threshold and start up afresh, and in this way she finally stumbled on the right spot by accident. This seemed very stupid of her, as she made many locality studies. Her behavior was in striking contrast to little Rhopalum’s unerring choice of one tiny pin-hole among hundreds just like it.
The larva of bombycina cocoons nine days after the egg is laid. The spiders that we found in the cells were dead even when taken on the day of storing. There was no rule about the degree of mutilation, one having seven legs left, two five, one two, and four none. We have no doubt that the object of this curious habit is to save room in the nest.