We have seen in the case of the Cerceres, the Sphex and the Ammophilæ how the mother solves the problem of preserved food-stuffs, the problem of stocking a cell with the requisite quantity of game for its future occupant and keeping the meat fresh for whole weeks at a time; indeed, it is something more than fresh, for the victims are kept in an almost living state, except that they are incapable of movement, an essential condition if the grub is to feed on them in safety. The miracle is performed by the most cunning methods known to physiology. The poisoned lancet is driven into the nerve-centres once or oftener, according to the structure of the nervous system. Thus operated upon, the victim retains all the attributes of life, short of the power of moving. Let us see if the Bembex make use of this profound science of slaughter. The Flies taken from between the legs of the kidnapper as she enters her burrow present, in most cases, every appearance of death. They are motionless; occasionally we can detect in a few of them some faint convulsions of the tarsi, the last vestiges of a life that is passing away. The same appearance of complete death is usually found in the insects which are not actually killed but paralysed by the adroit dagger-thrust of a Cerceris or a Sphex. The question whether they are alive or dead can therefore be decided only according to the manner in which the victims keep fresh. Placed in little screws of paper or in glass tubes, the Crickets and Grasshoppers of the Sphex, the caterpillars of the Ammophilæ, and the Beetles and Weevils of the Cerceres preserve their flexibility of limb, their freshness of colouring and the normal condition of their intestines for weeks and months. They are not corpses but bodies sunk in a lethargy from which there is no awaking. The Flies of the Bembex behave quite differently. The Eristales, the Syrphi—in short, all those whose livery is at all brightly coloured—soon lose the brilliancy of their attire. The eyes of certain Gad-flies, magnificently gilded, with three purple bands, very quickly grow pale and dim, like the eyes of a dying man. All these Flies, large and small, when placed in little paper bags through which the air circulates freely, dry up in two or three days and become brittle; all, when preserved against evaporation in glass tubes in which the air is stationary, go mouldy and decay. They are dead, therefore, really and truly dead, when the Wasp brings them to her larva. Should some of them still retain a remnant of life, a few days or even hours put an end to their agony. Consequently, for lack of talent in the use of her dagger or for some other reason, the murderess kills her victims outright.