Saw-flies, Gall-flies, Ichneumons, 



FIG. 719. Nest of 



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, 

 Feaf-'cutter bee, Me- perhaps, being the mason-bees (Osmia), the potter-bees 



gachile anthracina. (Anth'dium), and the leaf-cutters (Megachile) . The 



(After Sharp; some- \ 



what enlarged.) 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 are 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 Fl ?- 7 20 - Sin g le cel1 



..... in nest of leaf-cut- 



cut out pieces of green leaves with which they line the ter ] 3ee) Megachile 



tunnel and partition in such a way as to form a series anthracina. (After 

 of thimble-shaped cells each partially filled with a paste enlarged.) 801 

 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 



