“But the work can proceed quickly only so long as the Wasp is able to moisten the sand. She is obliged to take trouble to renew her store of water. I do not know whether she simply went to take in water at some stream, or whether she drew, from some plant or fruit, a more sticky fluid; what I do know is that she returned without delay and set to work with renewed zeal. I observed one Wasp who managed, in about an hour, to sink a hole the length of her body and who raised a chimney as tall as the hole was deep. At the end of a few hours the tube stood two inches high and she was still deepening the hole that lay underneath. “It did not appear to me that she had any rule respecting the depth which she gives it. I have found some whose hole ran more than four inches from the orifice; others whose hole measured only two or three inches. Again, over one hole you will find a tube twice or three times as long as that over another. Not all the mortar removed from the hole is invariably employed to prolong it. In cases where the Wasp has given the tube a length which she considers sufficient, you see her simply arrive at the opening to the tube, put her head beyond its edge and forthwith drop her pellet, which falls to the ground. In this way I have often observed a quantity of rubbish at the foot of certain holes. “The object for which the hole is pierced in a solid mass of mortar or sand cannot appear in doubt: it is plainly intended to receive an egg, together with a store of foodstuffs. But we do not so easily see to what end the mother has built the mortar shaft. By continuing to follow her labours, we shall discover that it means to her what a stack of well-laid stones means to the masons building a wall. Not the whole of the tunnel which she has excavated is intended as a lodging for the larva which will be born inside; a portion will be quite enough. Yet it was necessary that the hole should be dug to a certain depth, in order that the larva may not find itself exposed to too great a heat when the sun’s rays fall on the outer layer of sand. It will occupy only the end of the tunnel. The mother knows what space she must leave vacant and this space she retains; but she fills up all the remainder and replaces in the upper portion of the hole as much of the sand removed from it as is necessary to stop it up. It is to have this mortar within reach that she has built that shaft. Once the egg is laid and the store of victuals placed within its reach, we see the mother come and gnaw the end of the shaft, after first moistening it, carry the pellet inside and next return for more, in the same manner, until the hole is blocked right up to the opening.”