The nest is certainly there—underground, at the depth of a few inches: in a little cell, dug in cool firm sand, is an egg, perhaps a larva, which the mother feeds daily with flies, the invariable food of Bembex larvæ. She must be able at any moment to penetrate to this nest, carrying on the wing, between her feet, the nursling’s daily ration, just as a bird of prey arrives at its eyrie carrying game for its brood in its claw. But while the bird returns to a nest on some inaccessible shelf of rock, without any difficulty beyond the weight of its prey, the Bembex must undertake each time the hard work of mining, opening afresh a gallery blocked and closed by ever-sliding sand in proportion as she proceeds. The only stable part of this underground abode is the spacious cell inhabited by the larva amid the remains of a fortnight’s feast; the narrow vestibule entered by the mother to go down to the cell, or come forth for the chase, gives way each time, at all events at the upper end, built in dry sand, rendered even looser by her constant goings and comings. Thus at each entrance or exit the Hymenopteron must clear out a passage. The exit offers no difficulties, even should the sand have the same consistency as when first stirred; the insect’s movements are free; it is safe under cover, can take its time and use tarsi and mandibles at its leisure. Going in is another matter. The Bembex is embarrassed by her prey, pressed to her body by her feet, so that there is no free use of the mining tools. What is more serious is that impudent parasites—veritable bandits in ambush—are crouching here and there about the burrow watching her difficult entrance to hurriedly drop their egg on the game just as it disappears into the gallery. If they succeed, the son of the house, the Hymenopteron’s nursling, will perish, starved by greedy guests.