Wasps, Social and Solitary

by George W. Peckham; E. G. Peckham

THE BURROWERS

DUFOUR, in describing the fearful ravages of Cerceris ornata among the bees, says that the wasps of this genus are among other insects what eagles and hawks are among birds. While this characterization does not seem to fit the American species, it is certainly true that the genus stands out as one of those in which the distinctive peculiarities are strongly marked. They might be considered the aristocrats in the world of wasps, their habits of reposeful meditation and their calm, unhurried ways being far removed from the nervous manners of the Pompilidæ or the noisy, tumultuous life of Bembex. Their intelligence is shown by their reluctance to betray their nests, and by their uneasiness at any slight change in the objects that surround them. It is not necessary to attempt to catch them or to make threatening gestures, in order to arouse their sense of danger. If you are sitting quietly by a nest when the wasp opens her door in the morning she will notice you at once, and will probably drop out of sight as though she resented your intrusion into her privacy. After a little she will come up again and will learn to tolerate you, but at the least movement on your part, almost at the winking of an eyelid, she will disappear.[ill142]

NEST OF CERCERIS NIGRESCENS

Our four representatives of this genus all prey upon beetles that are injurious to vegetation, and therefore deserve the gratitude of agriculturists. Nigrescens, with her pale grayish bands, is a very trying wasp to deal with. We had seen her flying about in the garden for weeks before we succeeded in tracking her home, and when we did succeed she was so late about getting up in the morning, stayed away from home so many hours at a time, and went to bed so early in the afternoon, that we were not well repaid for watching her nest all day. Fumipennis, large and handsome, with a broad yellow band at the front of the abdomen, is another wasp that has no regard for the convenience of the people who are watching her. You may sit by her big open hole for hours without seeing her, and when she comes she drops in so suddenly that, unless you are very much on your guard, you are not sure even then what she is. Clypeata and deserta are better subjects for study.

The nests of our species are all deep, tortuous, and very difficult to excavate. We have never succeeded in finding their pockets; and yet, for various reasons, we feel perfectly certain that all of them are like C. ornata in provisioning, successively, a number of cells which lead out of the main gallery. When one of these cells is filled with food, and the egg deposited, it is probably closed up, and thus separated from the runway. From our experience late in the season with the nests of another wasp, we are inclined to think that we made a mistake in looking for pockets at the lower end of the tunnel. Had we searched higher up, at the point of the curve, we might have found them, the lower part of the gallery probably being designed merely for a dwelling-place for the mother of the family.[ill143]

CERCERIS CLYPEATA

But although we did not get distinct pockets, there was, in at least one nest, a supply of food that would have far exceeded the wants of a single larva. We did not succeed in finding eggs on different groups of beetles; but from a nest into which the wasp was still carrying food we took a half-grown larva which was identified as being hers. The fact, too, that a wasp occupies a nest for so long a time as ten days or two weeks points to the conclusion that she uses it for a number of eggs which are laid at intervals.

Cerceris digs her nest, deep as it is, all at once. In this she is a contrast to her near relatives of the genus Philanthus, who busy themselves for an hour or so every morning with fresh excavations.