The temporary closing of the burrow with a flat stone, as practised by the Sandy Ammophila and the Silvery Ammophila, is apparently unknown to the other two species. At any rate, I never saw their homes protected by a lid. Besides, this absence of a provisional door seems to be obligatory upon the Hairy Ammophila. In fact, as far as I could see, this species hunts its prey first and then digs its burrow near the place of capture. In this way the storing of the provisions can be done straight away; and there is no need to trouble about a lid. As for the Silky Ammophila, I suspect that she has another reason for not employing a temporary cover. Whereas the three others put only one caterpillar in each burrow, she puts in as many as five, though much smaller ones. Just as we ourselves neglect to shut a door through which we are constantly passing, so perhaps the Silky Ammophila neglects the precaution of placing a stone over a well down which she has to go at least five times in a short space of time. In the case of all four, the provisions of the larvæ consist of caterpillars of Moths. The Silky Ammophila selects, though not exclusively, those long, thin caterpillars which walk by looping and unlooping their bodies. Their gait suggests a pair of compasses that makes its way by opening and closing in turns. Hence they are known by two expressive names: Loopers and Measuring-worms. [32] The same burrow contains provisions varying greatly in colour, a proof that the Ammophila hunts without distinction every species of Loopers, provided that they be small, for the huntress herself is anything but large and her grub cannot get through very much, in spite of the five pieces of game set before her. If Loopers fail, the Wasp falls back on other equally slender caterpillars. Curved into a hoop as the result of the sting that paralysed them, the five pieces are stacked up in the cell: the uppermost carries the egg for which the provisions are made. The three other Ammophilæ give only one caterpillar to each larva. It is true that here bulk makes up for number: the game selected is big, plump, capable of amply satisfying the grub’s appetite. For instance, I have taken from the mandibles of the Sandy Ammophila a caterpillar weighing fifteen times as much as its captor: fifteen times, an enormous figure when we consider the strength which the huntress must expend in dragging game of this kind by the skin of the neck over the countless obstacles on the road. No other Wasp, tried in the balance with her prey, has shown me a like disproportion between spoiler and booty.