Amongst the best known of the solitary species of bees are the Carpenter Bees, the Carding and Tapestry Bees, and the Mason Bees. Of the latter a great French observer, who, though he lives now, belongs really to the days of Réaumur and Swammerdam, has something to tell us. Speaking not of Réaumur’s maison bee—that “splendid Hymenopteron with its dark violet wings and costume of black velvet”[86]—but of a smaller species—_Chalicodoma sicula_—he says: “You should see the active bee at work when the road is dazzling white in the hot sunshine. Between the neighbouring farm where she is building and the road where the mortar is prepared there is a deep hum of the bees perpetually crossing each other as they come and go. The air seems traversed by constant trails of smoke, so rapid and direct is their flight. Those who go carry away a pellet of mortar as big as small shot: those who come settle on the hardest and driest spots. Their whole body vibrates as they scratch with the tips of their mandibles and rake with their forefeet to extract atoms of earth and grains of sand, which, being rolled between their teeth, become moist with saliva, and unite. They work with such ardour that they will let themselves be crushed under the foot of a passer-by rather than move.”[86] Then comes the making of the actual nest, or little collection of cells. “After choosing a boulder,” says Fabre, “she comes with a pellet of mortar in her mandibles, and arranges it in a ring on the surface of the pebble. The forefeet, and, above all, the mandibles, which are her most important tools, work the material, which is kept plastic by the gradually disgorged saliva. To consolidate the unbaked clay, angular pieces of gravel as large as a small bean are worked in singly on the outside of the still soft mass. This is the foundation of the edifice. Other layers are added, until the cell has the required height of three or four centimetres. The masonry is formed by stones laid on one another and cemented with lime, and can stand comparison with our own. Layers of mortar sparingly used hold them together. The cell completed, the bee sets to work at once to store it. The neighbouring flowers, especially those of _Genista scorpius_, which in May turn the alluviums of the torrents golden, furnish sugared liquids and pollen. She comes with her crop swelled with honey, and all yellow underneath with pollen dust, and plunges head first into the cell, where for some moments one may see her work her body in a way which tells that she is disgorging honey. Her crop emptied, she comes out, but only to go in again at once, this time backwards. With her two hind feet she now frees herself from her load of pollen by brushing herself underneath. Again she goes out, and returns head first. She must stir the materials with her mandibles for a spoon, and mix all thoroughly together. When the cell is half full it is stored; an egg must be laid on the honey paste, and the door has to be closed.