The New International Encyclopædia/Mason Bee

MASON BEE. A bee of the sub-family Osmiinæ of the family Megachilidæ; especially in the United States one of the genus Osmia, and in Europe one of the genus Chalicodoma. The name is derived from the manner in which these bees construct small earthen cells, sometimes mixed with sand, pebbles, and wood-scrapings, glued together so firmly that they are smooth inside. Ten to twenty of the cells are usually found together, and each one contains a store of honey and pollen for the larvæ, only one of which is found in each of the cells. These bees show a high order of intelligence in the manner in which they adapt themselves to circumstances, and this accounts for the very great diversity seen in the situations in which the cells are placed. Ceratosmia lignivora is a true wood-borer. Certain species excavate the pith of brambles, alternately widening and contracting the burrow to correspond with the proposed cells and the intervals between them. Others use the hollows of reeds and straws; two European species utilize the empty shells of several species of Helix, compactly filling each shell with their cells, which are placed in different relative positions according to the exigencies of the case, and then carefully closing the entrance with pellets of clay, sticks, and pebbles; others again plaster their cells thickly upon the under side of a flat stone which is slightly raised from the ground; and still another species places its cells in comparatively unprotected situations at the roots of grass. The Chalicodomas make very perfect mason work in the walls of their cells.

The food stored up in the cells is composed of a mixture of honey and pollen, Réaumur and Fabre experimented with the young bees to find whether they were able to overcome additional difficulties in making their way out of the cell. When the mouth of the cell is covered with earth and pith or brown paper put in contact with the covering of the cells, the bees make their way out without any great apparent difficulty, but when some space intervenes between the mouth of the cell and the new barrier, the bees are unable to gain their freedom. The Osmiinæ are of comparatively small size, and are usually of dark metallic colors. The eggs are white, oblong, and about the size and shape of a caraway seed. They hatch in about eight days. Development of the larvæ is rapid; they spin delicate cocoons and winter as pupæ.

Consult: Fabre, Insect Life, translated from the French (London, 1901); Howard, Standard

Natural History, vol. ii. (Boston, 1884); Howard, The Insect Book (New York, 1901). See Plate of.