The protective sheath, which is also a framework, is not the work of the mother. Like the great majority of the Osmiae, the Megachiles do not understand the art of making themselves a home straight away: they want a borrowed lodging, which may vary considerably in character. The deserted galleries of the Anthophorae, the burrows of the fat Earth-worms, the tunnels bored in the trunks of trees by the larva of the Cerambyx-beetle (The Capricorn, the essay on which has not yet been published in English.--Translator's Note.), the ruined dwellings of the Mason-bee of the Pebbles, the Snail-shell nests of the Three-horned Osmia, reed-stumps, when these are handy, and crevices in the walls are all so many homes for the Leaf-cutters, who choose this or that establishment according to the tastes of their particular genus. For the sake of clearness, let us cease generalizing and direct our attention to a definite species. I first selected the White-girdled Leaf-cutter (Megachile albocincta, PEREZ), not on account of any exceptional peculiarities, but solely because this is the Bee most often mentioned in my notes. Her customary dwelling is the tunnel of an Earth-worm opening on some clay bank. Whether perpendicular or slanting, this tunnel runs down to an indefinite depth, where the climate would be too damp for the Bee. Besides, when the time comes for the hatching of the adult insect, its emergence would be fraught with peril if it had to climb up from a deep pit through crumbling rubbish. The Leaf-cutter, therefore, uses only the front portion of the Worm's gallery, two decimetres at most. (7.8 inches.--Translator's Note.) What is to be done with the rest of the tunnel? It is an ascending shaft, tempting to an enemy; and some underground ravager might come this way and destroy the nest by attacking the row of cells at the back. The danger is foreseen. Before fashioning her first honey-bag, the Bee blocks the passage with a strong barricade composed of the only materials used in the Leaf-cutter's guild. Fragments of leaves are piled up in no particular order, but in sufficient quantities to make a serious obstacle. It is not unusual to find in the leafy rampart some dozens of pieces rolled into screws and fitting into one another like a stack of cylindrical wafers. For this work of fortification, artistic refinement seems superfluous; at any rate, the pieces of leaves are for the most part irregular. You can see that the insect has cut them out hurriedly, unmethodically and on a different pattern from that of the pieces intended for the cells.