Placed in little paper twists or glass tubes, the Orthoptera of the Sphex, the caterpillars of the Ammophila, the Coleoptera of the Cerceris, preserve flexibility of limb and freshness of colour, and the normal state of their intestines, for weeks and months. They are not corpses, but bodies plunged in a lethargy from which there will be no awakening. The Diptera of the Bembex behave quite otherwise. Eristalis, Syrphus,—in short, all which are brightly coloured,—soon lose their brilliance; the eyes of certain gadflies, magnificently gilded, and with three purple bands, soon grow pale and dim, like the gaze of a dying man. All these Diptera, great and small, placed in paper twists where air circulates, dry up and grow brittle in two or three days, while all kept from evaporation in glass tubes, where the air is stagnant, grow mouldy and decay. So they are dead—really dead—when carried to the larva. If some few preserve a little life, a few days, a few hours ends all. Not being clever enough to use its sting, or for some other reason, the assassin kills its victims outright. Knowing this complete death of the prey at the moment when it is seized, who would not admire the logic of the Bembecid’s manœuvres? How methodical all is, and how one thing brings about another in all which the wary Hymenopteron does! As the food could not be stored without its decaying at the end of two or three days, it cannot be laid in wholesale at the beginning of a phase of life destined to last at least a fortnight, and there must be a hunt and distribution of provisions day by day, in proportion to the larva’s growth. The first ration—that on which the egg is laid—will last longer than the others, and must be small, for the little grub will take several days to eat it, and if too big it would go bad before it was finished. Therefore it will not be a huge gadfly or a corpulent Bombylius, but a small Sphærophoria, or something of that kind, as a tender meal for a still frail larva. Later, and gradually larger, will come the bigger joints. In the mother’s absence the burrow must be closed to prevent awkward intrusions, but the entrance must be one opened quickly, without serious difficulty, when the Hymenopteron returns loaded with prey, and laid in wait for by audacious parasites. These conditions would be wanting in a tenacious soil, such as that in which the mining Hymenoptera habitually establish themselves. The wide-open entrance would each time require long and painful labour, whether to close it with earth or gravel, or to clear it. The domicile, therefore, must be hollowed in earth with a very light surface, in dry, fine sand, yielding at once to the least effort of the mother, and which slips and closes the entrance like floating tapestry, which, pushed back by the hand, allows entrance and then drops back. Such is the sequence of acts, deduced by human reason, and put into practice by the wisdom of the Bembex.