5H 



Saw-riies, Gall-Hies, Ichneumons, 



Fig. 7). They are as large as bumblebees and with their heavy thick 

 body and black color look much like them; they have 

 the body more flattened and less hairy, however, and the 

 hind legs of the females are never provided with a 

 "corbiculum," or pollen-basket (a concave smooth 

 place bounded on each side by a row of long stiff curv- 

 ing hairs), but are covered by a stiff brush of short 

 hairs. These giant bee-carpenters tunnel into solid 

 wood for a foot or more, dividing the burrow into a 

 series of cells by partitions made of small chips stuck 

 together. They are common all over the country, 

 "choosing in civilized regions fence-posts and boards." 

 Certain very large species make their nests in the 

 great fallen sugar-pines and yellow pines of the Sier- 

 ran forests and are among the most characteristic in- 

 sects of the giant-tree forests. 



The long-tongued family Megachilidae includes a 

 number of common and interesting bees, most familiar, 

 perhaps, being the mason-bees (Osmia), the potter-bees 

 (.•\nth.dium), and the leaf-cutters (Megachile). The 

 Osmias are metallic, black, blue, or green, and make 

 their nests of clay and sand, moulded into cells, and 



built in already existing cavities in stone walls, old posts, tree-trunks, etc., 



or in tunnels bored by the bee in plant-stems and twigs. The various 



species of Anthidium arc black and rufous, or rufous 



and yellow, with the abdomen always banded or spotted 



with yellow, white or rufous. The females normally 



construct globular cells rather like the earthen vases 



of Eumenes (Fig. 701), but made of the resinous exuda- 

 tions of pine-trees and other plants, or dig burrows in 



the soil which they line with down stripped from 



pudescent or woolly-leafed plants. Both Osmia and 



Anthidium sometimes make their nests in deserted 



snail-shells! The leaf-cutting bees (Figs 719 and 720) 



are usually carpenters as well as tailors; that is, they first 



bore a tunnel in some plant-stem or in wood, and then 



cut out pieces of green leaves with which they line the 



tunnel and partition in such a way as to form a series 



of thimble-shaped cells each partially filled with a paste 



of pollen and nectar on which an egg is deposited. The 



pieces of leaf are fastened together with a gummy secretion from the mouth 



of the bee. Comstock has found leaf-cutter nests in a "crack between 



Fig. 719. — Nest of 

 leaf-cutter bee, Me- 

 gachile anthracina. 

 (After Sharp; some- 

 what enlarged.) 



Fig. 720. — Single cell 

 in nest of leaf-cut- 

 ter bee. Megach He 

 anthracina. (.\fter 

 Sharp; somewhat 

 enlarged.) 



