For all four the burrow is a vertical shaft, a kind of well, with at most the dimension of a large goose quill, and about two inches deep. At the bottom is a single cell, formed by a simple widening of the shaft. To sum up, it is a poor dwelling, obtained at small expense, at one sitting, affording no protection if the larva had not four wrappers in its cocoon, like the Sphex. The Ammophila excavates alone, deliberately, with no joyous ardour. As usual, the anterior tarsi do duty as rakes and the mandibles as mining tools. If some grain of sand offer too much resistance, you may hear rising from the bottom of the well a kind of shrill grinding sound, produced by the vibration of the wings and entire body as if to express the insect’s struggles. Frequently the Hymenopteron comes up with a load of refuse in its jaws, some bit of gravel which it drops as it flies some little way off, in order not to block up the place. Some appear to merit special attention by their form and size,—at least the Ammophila does not treat them like the rest, for instead of carrying them away on the wing, she goes on foot and drops them near the shaft. They are choice material—blocks ready prepared to stop up the dwelling by and by. This outside work is done with a self-contained air and great diligence. High on its legs, its abdomen outstretched at the end of its long petiole, it turns round and moves its whole body at once with the geometrical stiffness of a line revolving on itself. If it has to throw away to a distance the rubbish it decides to be only encumbrances, it does this with little silent flights, often backwards, as if, having come out of the shaft tail first, it thought to save time by not turning round. Species with long-stalked bodies, like A. sabulosa and A. argentata, are those that chiefly display this automaton-like rigidity. Their abdomen, enlarged to a pear-shape at the end of a thread, is very troublesome to manage; a sudden movement might injure the fine stalk, and the insect has to walk with a kind of geometrical precision, and if it flies, it goes backward to avoid tacking too often. On the other hand, A. hirsuta, which has an abdomen with a short petiole, works at its burrow with swift easy movements such as one admires in most of the miners. It can move more freely, not being embarrassed by its abdomen.