closes up the orifice, and proceeds to prepare the third. This work is pushed on with great activity, and when completed the _Sphex_ entirely fills up the subterranean passage, and completely isolates the hope of the race at a depth sufficient to shelter it well. A last precaution is taken: before leaving, the rubbish in front of the obstructed opening is cleared away, and every trace of the operation disappears. The nest is then definitely abandoned, and another one prepared. [72] "Etude sur l'instinct et les metamorphoses des Sphegiens," _Ann. Sci. Nat._, 1856. The chambers in which the larvae are enclosed--hastily made with little care, and with rough unsmoothed walls--are not very solid, and could not last long without slipping; but as they only have to last for a single season they possess sufficient resistance for the insect's purpose. The larva also knows very well how to protect itself against the roughness of the walls, and overlays them with a silky secretion produced by its glands. We have now to consider the nature of the provisions placed by the _Sphex_ near the egg. Each cell must contain four crickets. That is the amount of food necessary for a larva during its evolution, and these insects are in fact large enough to supply a considerable amount of nourishment. When the _Sphex_ interrupts digging operations it is to fly on a hunting expedition. It soon returns with a cricket it has seized, holding it by one antenna which it turns round in its jaws. It is a heavy burden for the slender _Sphex_ to bear. Sometimes on foot, dragging its burden after it, sometimes flying, and carrying the suspended cricket always in a passive condition, the burrow is gradually reached, not without difficulty. In spite of appearances, the cricket is not dead; it cannot move, but if kept for several days it will not putrefy, and its joints remain supple. It is simply the victim of a general paralysis.