Wasps, Social and Solitary

by George W. Peckham; E. G. Peckham

We once saw a wasp of this species digging her nest on the Bembex field. When finished it was a large hole which could not have been distinguished from those of spinolæ, which were open all about, the weather being bright and sunny. She flew off, and soon reappeared with her spider, which was dropped three feet away while she ran to make sure that all was right; and now followed something that we had never seen before—she could not find her nest. She flew, she ran, she scurried here and there, but she had utterly lost track of it. She approached it several times, but there are no landmarks on the Bembex field. We have often wondered how they find their own places. After five minutes our wasp flew back to look at her spider, and then returned to her search. She now began to run into the Bembex holes, but soon came out again, even when not chased out by the proprietor. Suddenly it seemed to strike her that this was going to be a prolonged affair, and that her treasure was exposed to danger; and hurrying back she dragged it into the grass at the edge of the field, where it was hidden. Again she resumed the hunt, flying wildly now all over the field, running into wrong holes and even kicking out earth as though she thought of appropriating them, but soon passing on. Once more she became anxious about the spider, and carrying it up on to a plant suspended it there. Now she seemed determined to take possession of every hole that she went into, digging quite persistently in each, but then giving it up. On one that seemed to be unoccupied she labored at enlarging the entrance, until we thought that she had mistaken it for her own, or at least had determined to use it. At last, however, she made up her mind that all further search was hopeless and that she must start afresh; and forty minutes from the time that we saw her first she began a new nest close to the spider, as though she would run no more risks. This nest was successfully completed, and the spider was stored away without further misadventure.

The egg of quinquenotatus can be but lightly attached to the spider, for only once, out of many attempts, did we succeed in getting it out without displacing it. In this case three days elapsed before it hatched. The larva ate for a day or two, but then pined away and died. Another nest was opened on the tenth day after the egg was laid, and in this the spider had been entirely eaten and the larva was just spinning its cocoon; so that the larval stage probably occupies about a week.

A summary of our notes shows a very wide variation in the condition of the spiders stored by this wasp. Out of eleven that were stung three were killed at once, two lived four days, one five, one eleven, one twenty-three, one twenty-five, one thirty-one, and one at least forty days and probably longer.

We look back with much pleasure upon our acquaintance with this gay, excitable little wasp. She was so full of breezy energy that it was always delightful to meet her, and she showed so wide a variation in individual character that we seldom watched her without learning something new.

Pompilus fuscipennis, a little smaller than P. quinquenotatus, is black, with the red girdle that appears so frequently among the solitary wasps. The first time that we ever saw this wasp she was running rapidly backward over the bare ground, the brilliant red of her body flashing in the sunlight as she dragged along a little spider of the genus Thomisus. Presently she carried it up on to a leaf and began to bite at it, but being disturbed by an ant, hurried on with a much agitated manner. Soon she stopped again and resumed her attack, biting savagely at the legs near their junction with the body, and now, looking closely, we saw that two of them had been completely cut off. While occupied in this way the wasp was evidently intensely excited. She lay on one side with the abdomen bent under, turning the spider over and over as she worked. After a time she carried it onward to the potato-field, where the plants afforded some shelter, and placing it upon a leaf, well above the ground, began to dig near by. She worked almost entirely with her mandibles, lying sometimes on her side and sometimes on her back as she cut away the earth, which was pushed out with the end of her abdomen. When she had worked for ten minutes and had gone in the length of her body, she picked up the spider and rapidly made off with it, several times rising on her wings and flying backward for a few inches. A little further along she again deposited it on a leaf and began to dig in a fresh place. At the end of twenty minutes the nest was ready, but in bringing the spider she missed her direction and carried it to one side. Dropping it on the ground, she began to hunt about for her hole, but was distracted with excitement and ran so far afield that we feared she would never find it. At last, however, she came to the place, ran in for a moment, brought the spider nearer, dropped it and ran to the nest once more, caught it up again, and tried to back in with it. She was holding it by the under side of the body, the venter being toward the hole, and the legs spread out and stopped its entrance. A moment’s tugging convinced her that this would not do, and she then turned the spider over, holding it by the back, whereupon the legs at once folded themselves across the underside of the thorax, and it was drawn out of sight.

After the egg was laid the wasp came up to the edge of the hole, and drawing in some earth with her mandibles began to dance up and down upon it, jamming it into place with her abdomen. Afterwards she came up higher and drew the dirt in with her first legs, not getting out of the hole until it was entirely filled up. Then began a remarkable performance. Bracing herself firmly on her legs she used the end of her abdomen as an instrument, and with it she now pounded the earth, now rubbed it, like a pestle in a mortar, and now used it as a brush to sweep away loose dust. Sometimes she would throw a little earth back under her body with her mandibles and rub it down with her abdomen. This part of the work being finished, she spent a few minutes in sweeping the ground with her first legs, and then brought a quantity of small objects and placed them over the nest,—a little stick, the petal of a faded flower, a scrap of dead leaf, and so on, until ten or twelve things had been collected. This artistic finishing up of her duties recalled Ammophila; but among our subsequent examples of fuscipennis we never saw one do her work with such nicety. They were usually contented to fill in the nest more or less compactly, sometimes doing much of the work from the outside, to brush off the surface without any rubbing or pounding, and then to bring two or three little pebbles or lumps of earth to place over the spot.

So far as we were concerned this was one of the most fearless of the wasps, not even interrupting her work when we once placed a glass over her as she was filling her nest; but the approach of an ant would throw her into a perfect panic, and seizing her spider she would make off with every sign of terror. It is difficult to understand why wasps of this species, as well as of biguttatus, never offer combat to the ants that rob them right and left, but invariably seek safety in retreat. Their attitude toward other robbers is quite different. We once saw a fuscipennis that was dragging a Lycosid attacked by a bigger wasp of the same species. Number One left her spider on the ground and chased Number Two to a distance; but no sooner had she returned and taken it up than Number Two, bold and unashamed, was at her heels again, and the scene was repeated. The object of the robber was to seize a leg of the spider, and whenever she succeeded in doing this she jerked it free, and made off with it very rapidly; but when the owner pursued and caught up with her she relinquished the prize without a struggle. Why did she? She was the bigger and the stronger, and possession is nine points of the law in Waspland as elsewhere; but conscience made a coward of her, while the other was strong in her righteous cause. After a time we captured the little pirate; but now the nerves of the rightful owner were completely upset, and she flew away, deserting the spider for which she had battled so bravely.

The most interesting thing about fuscipennis is her habit of biting the legs of her victims. The instinct is very irregularly developed, since four out of ten spiders had not lost any legs, while the others had been deprived of one or two. No one who has watched the wasp can doubt that the habit is related to the fact that she makes a very small nest in comparison to the size of her prey. The spider never went in easily, always requiring to be shifted and turned and tugged at. There was an especial tendency to bite at the legs at this point of time, when the wasp, standing within the tunnel, was trying to drag the spider down. In one instance she managed to get it past the entrance, but it stuck in the gallery; and after working at it in that position for a time she brought it out, subjected the legs to a severe squeezing, and then tried again. It was still a very bad fit, but by turning it about and pulling at it she succeeded in getting it in. It may be that the object of biting the legs is not to remove them, but to render them limber so that they will bend easily. Whatever the process may be, it is repeated at intervals from the time the spider is captured. As she carries it, the wasp pauses again and again, now on bare ground and now in a sheltered place or on some plant, to renew her efforts at getting the legs into a satisfactory state.

P. fuscipennis rarely circles about when leaving a place; this is unfortunate, since her sense of locality seems to be particularly weak. She nearly always has to hunt for the plant upon which she has placed her spider, and always loses track of her nest when she tries to bring the spider to it. We once caught her as she was carrying her spider, and then released her on the same spot; but she became so much confused that without our assistance she would never have found it again.

Our acquaintance with Pompilus marginatus began in the middle of July. She is a small creature, only half an inch long, and is dressed in black, with a bright orange spot on each side of the anterior part of the abdomen. We were watching the pretty little Diodonti, as they filled their holes with aphides, when we saw her going backward, dragging along a medium-sized spider. Soon she came to an onion flower that was lying on the ground. Here she stopped and, after a moment’s hesitation, drew her prey in among the blossoms of the cluster so that it was hidden from view. It was not long before she came out and began to fly about near the ground, frequently alighting to poke her head into cracks and to run again and again into little chance holes. Never did an insect behave in a more demented manner, and although there may have been a method in her madness it was difficult to discover it. No hole nor cranny pleased her, and back she flew to the onion to see whether her booty were safe. For fifteen minutes she ran and flew now here, now there, hurry and anxiety in every movement, returning frequently to reassure herself about the spider. Several times she entered a hole at the base of a weed, not a made nest, but an accidental crevice; and this spot was at length chosen either as a temporary or a final resting place for her spider, since she dragged it from the onion and deposited it here. We tried to capture the wasp; but having failed in this, we dug out the spider. It was three inches down, the hole being deeper than it looked from the outside. There was no egg upon it. Evidently the work had not been finished, for the restless creature returned fifteen times within an hour to the broken nest, either for the purpose of laying her egg or to remove the spider to another resting-place on her homeward way.[ill223]