mason bee

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various solitary bees of the family Megachilidae that build nests from mud, chewed leaves, or resin.

from The Century Dictionary.

• noun An aculeate hymenopterous insect of one of the genera Anthophora, Osmia, Chalicodoma, and some others, which construct their nests with grains of sand agglutinated together by means of a viscid saliva, and fix them on the side of walls, etc., or avail themselves of some cavity for that purpose. See cut under Anthophora.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology Any of the bees of the genus Osmia, which have the habit of making compartments of mud in their nests.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of numerous solitary bees that build nests of hardened mud and sand