Bembex, like Philanthus, and some species of Sphex, lives in a sort of semi–social state, a number of individuals occupying the same space of ground, although each one has its separate nest. Bembex, however, differs from these genera and from almost all of the solitary wasps in her habit of feeding her young from day to day, or rather from hour to hour, as long as it remains in the larval state. This difference in her maternal cares as compared with those of other species results in a less numerous progeny. The larva, for a period of two weeks, demands constant attention from the mother, so that a second egg cannot be laid until the first–born has gone into its cocoon, unless, indeed, she feeds two larvæ at once, which does not seem probable. The season of work is ten or twelve weeks, so that Wesenberg is probably correct in allowing only five or six young ones to each mother for the summer. In watching our wasps we found that the new nests were usually made in the outskirts of the colony, which was thus continually extending its limits. Like many other species, Bembex has great difficulty in deciding just where to dig. Our Sphex made three beginnings before finally settling down. The only Ammophila that we watched from the beginning changed her place after working for ten minutes. P. quinquenotatus often tried half a dozen places before she was satisfied, and spinolæ is quite as difficult to please. When, at last, the right place is found, the labor of excavation is carried on vigorously. The mandibles are used for loosening the earth, and for lifting, but the greater part of the work is done with the first pair of legs, the tarsi of which are doubled up while the dirt is swept out with the brush of stiff spiny hairs on the second joint. This attitude gives them a very comical aspect, making them look as if they were sweeping with their elbows. They sometimes lie far over to one side while loosening the earth with their mandibles. While digging, the body is held high by the straightening of the third pair of legs, and the dirt comes out behind in a rapid stream, flying to a distance of three or four inches. Before long the wasp is lost to sight, but every few moments she comes backing out, pushing behind her the dirt that she has displaced below. In about fifteen minutes the nest is ready, and the wasp turns her attention to scattering all the dirt that has been thrown out, sweeping the ground clean so that no sign of her work remains. We have often speculated as to the meaning of the careful and conscientious performance of this part of her task. With the wasps that nest by themselves it is not easy to see what enemy they are providing against in hiding the entrance to the nest; but the precaution seems still less necessary—even absurd—in the Bembex field, where there is no possibility of concealing the colony, and where the nests are only an inch or two apart, so that an enemy might burrow anywhere with the certainty of finding one.