Wasps, Social and Solitary

by George W. Peckham; E. G. Peckham

“... the good old rule
Sufficeth them, the simple plan
That they should take who have the power
And they should keep who can.”

We once found an unusually tiny biguttatus vainly trying to drag a large Epeirid which her sting had reduced to helplessness. It was as though a feeble child should try to move the body of an elephant. The little wasp clasped one of the spider’s legs firmly in her mandibles, and then with braced feet and the wildest flutter of wings made gallant but futile attempts to get it started. Now she lost her hold on the ground, and wings and legs were all whirling desperately in the air. Now her feet grasped a loose ball of earth, and, feeling that something was moving, she renewed her efforts. The pellet was drawn nearer and began to rotate around the wasp, while she seemed to be under the impression that she was moving forward. After a few minutes of vigorous exercise, she paused, perhaps to see how she was getting on, and the bit of earth rolled away; so that when the attack was renewed, it was under the old discouraging conditions. She was the impersonation of perseverance and energy; but after half an hour (no one knows how long she had been at it before we came) she gave it up, and with many reluctant circlings flew away. It was probably experiences of this kind that developed in some of her relatives the habit of digging the grave under the victim, and thus saving the trouble of transportation.

At another time, we saw a biguttatus trying to run backward with a little bit of a spider, which she had lifted from the ground and was carrying in her mandibles,—trying to run backward, because it is the rule with this genus to move in that way when encumbered with a load, it being easier to drag a heavy spider than to pick it up and go forward. The wasp in question was drawn in two directions. Instinct made her go backward, although in this particular case it was needless, while she felt a constant desire to turn and go straight ahead. As a result she waltzed slowly over the sand in a series of overlapping circles, her head turned toward every point of the compass in succession, a kind of progress most amusing to the lookers-on.

Biguttatus is not strong enough to fly when laden, but it is the habit of the species to climb backwards to the top of every obstacle in the path, and from this vantage point to gain time by taking a downward flight in the direction of the nest. It is only in the case of tall, smooth-stemmed plants and grasses that the advantage gained is enough to repay the trouble of climbing, and we have often thought that the notion costs the wasp more trouble than it is worth,—as was certainly the case with one comical little creature that carried the idea to the extreme of folly. Not only did she scale objects in her way, but just as old Dr. Johnson felt that he had to touch every tree and post as he walked along, so when this wasp saw, out of the corner of her eye, a stone or a plant three or four inches to one side, it called upon her to climb, and climb she did, although she was obliged to leave her proper path to do it.

It is obviously more difficult to distinguish actions of intelligence than of instinct. One must be familiar with the normal conditions of the insects in question before he is able to note those slight changes in the environment that offer some opportunity for an adaptation of means to ends, or before he is competent to devise experiments which will test their powers in this direction.

We find two classes of intelligent actions among the Hymenoptera which are sufficiently distinct to be considered separately, although, like all natural groups, they grade into each other. The first of these includes those actions that are performed by large numbers in a similar fashion under like conditions, while in the second class each act is an individual affair,—as where a single wasp, uninfluenced in any way by the example of those about it, displays unusual intelligence in grappling with the affairs of life. Examples of the first class are found in such modifications of instinct as are shown by Pelopæus and other wasps in the character of their habitations. Pelopæus, instead of building in hollow trees or under shelving rocks, as was the ancient custom of the race, now nests in chimneys, or under the eaves of buildings. We have found T. rubrocinctum taking advantage of the face of a straw-stack that had been cut off smoothly as the cattle were fed through the winter. The same power of adaptation is shown by Fabre’s experiment with Osmia, in which he took two dozen nests in shells from a quarry, where the bees had been nesting for centuries, and placed them in his study along with some empty shells and some hollow stems. When the bees came out, in the spring, nearly all of them selected the stalks to build in as being better suited to their use than the shells. All of these changes are intelligent adaptations to new modes of life, serving to keep the species in harmony with its surroundings. The same thing may be seen when a number of social wasps work together to replace the roof of their nest when it has been torn off.

An instance of the second class is seen in one of our examples of Pompilus marginatus. This species, while searching for a nesting-place, leaves its spider lying on the ground or hides it under a lump of earth, in either of which positions the booty is subject to the attacks of ants; the wasp in question improved upon the custom of her tribe by carrying the spider up into a plant and hanging it there. We have now and then seen a queen of Polistes fusca occupy a comb of the previous year instead of building a new one for herself,—showing a better mental equipment than her sisters who were not strong-minded enough to change their ways, and so built new nests alongside of unoccupied old ones which were in good condition. In Bembex society it is good form to close the door on leaving home, but sometimes a wasp will save time by leaving the entrance open. This, however, is a doubtful case, as the advantage would, perhaps, be more than balanced by the exposure of the nest to parasites.

Some years after our first experience with Pompilus scelestus we saw a wasp of this species carrying her spider home. She dropped it close to the nest, and looked meditatively, first at the hole and then at the spider. It was unquestionably going to be a very tight fit, but if she could get it in that would be an advantage; so after a moment she seized it by the tip of the abdomen and backing down tried to pull it after. Tug—tug! No, it would not go down, and scelestus pushed it out and carried it to a place of safety up among some clover blossoms. She then washed and brushed herself neatly, and took several little walks, so that it was fully fifteen minutes before she began to enlarge her nest. All that time she must have carried in her little scrap of a mind the idea of doing a necessary act which was outside of her ordinary routine; and we noted with interest that the change when it was made accomplished exactly what was needed,—the spider went in, but not too easily.

In an experiment with a French Sphex which has the habit of laying her cricket down at the threshold, and going inside for an instant before dragging it in, Fabre took advantage of the moment that the wasp was out of sight below to move her prey to a little distance, with the result that when the wasp came up she brought her cricket to the same spot and left it as before, while she visited the interior of the nest. Since he repeated this experiment about forty times and always with the same result, it seemed fair to draw the conclusion that nothing less than the performance of a certain series of acts in a certain order would satisfy her impulse. She must place her prey just so close to the doorway; she must then descend to examine the nest; and after that she must at once drag it down, any disturbance of this routine causing her to refuse to proceed. We once found a Sphex ichneumonea at work storing her nest, and thought it would be interesting to pursue Fabre’s method and find out whether she were equally persistent in following her regular routine. We allowed her to carry in one grasshopper to establish her normal method of procedure, and found that, bringing it on the wing, she dropped it about six inches away, ran into the nest, out again and over to the grasshopper, which she straddled and carried by the head to the entrance. She then ran down head first, turned around, came up, and seizing it by the head, pulled it within. On the following day, when she had brought a grasshopper to the entrance of the nest, and while she was below, we moved it back five or six inches. When she came out, she carried it to the same spot and went down as before. We removed it again, with the same result, and the performance was repeated a third and a fourth time, but the fifth time that she had found her prey where we had placed it she seized it by the head, and going backward dragged it down into the nest without pausing. On the next day the experiment was repeated. After we had moved the grasshopper away four times, she carried it into the nest, going head foremost. On the fourth and last day of our experiment, she replaced the grasshopper at the door of the nest and ran inside seven times, but then seized it and dragged it in, going backward. How shall this change in a long-established custom be explained, except by saying that her intelligence led her to adapt herself to circumstances? She was enough of a conservative to prefer the old way, but was not such a slave to custom as to be unable to vary it.