The Mason-bee of the Pebbles does not make up her mind to build a brand-new dome unless there be a dearth of old and not quite dilapidated nests. The mothers, sisters apparently and heirs-at-law to the domain, dispute fiercely for the ancestral abode. The first who, by sheer brute force, takes possession of the dome, perches upon it and, for long hours, watches events while polishing her wings. If some claimant puts in an appearance, forthwith the other turns her out with a volley of blows. In this way the old nests are employed so long as they have not become uninhabitable hovels. Without being equally jealous of the maternal inheritance, the Mason-bee of the Sheds eagerly uses the cells whence her generation issued. The work in the huge city under the eaves begins thus: the old cells, of which, by the way, the good-natured owner yields a portion to Latreille's Osmia and to the Three-horned Osmia alike, are first made clean and wholesome and cleared of broken plaster and then provisioned and shut. When all the accessible chambers are occupied, the actual building begins with a new stratum of cells upon the former edifice, which becomes more and more massive from year to year. The Mason-bee of the Shrubs, with her spherical nests hardly larger than walnuts, puzzled me at first. Does she use the old buildings or does she abandon them for good? To-day perplexity makes way for certainty: she uses them very readily. I have several times surprised her lodging her family in the empty rooms of a nest where she was doubtless born herself. Like her kinswoman of the Pebbles, she returns to the native dwelling and fights for its possession. Also, like the dome-builder, she is an anchorite and prefers to cultivate the lean inheritance alone. Sometimes, however, the nest is of exceptional size and harbours a crowd of occupants, who live in peace, each attending to her business, as in the colossal hives in the sheds. Should the colony be at all numerous and the estate descend to two or three generations in succession, with a fresh layer of masonry each year, the normal walnut-sized nest becomes a ball as large as a man's two fists. I have gathered on a pine-tree a nest of the Mason-bee of the Shrubs that weighed a kilogram (2.205 pounds avoirdupois.--Translator's Note.) and was the size of a child's head. A twig hardly thicker than a straw served as its support. The casual sight of that lump swinging over the spot on which I had sat down made me think of the mishap that befell Garo. (The hero of La Fontaine's fable, "Le Gland et la Citrouille," who wondered why acorns grew on such tall trees and pumpkins on such low vines, until he fell asleep under one of the latter and a pumpkin dropped upon his nose.--Translator's Note.) If such nests were plentiful in the trees, any one seeking the shade would run a serious risk of having his head smashed.