Insects 203 



noted that this is on the surface of the body, and is not due to 

 hair. The French naturalist Fabre long ago remarked that the 

 bees called Anthidium belonged to two groups. One used cottony 

 material, scraped from the stems of plants, in preparing its nest, 

 which was in a burrow. The other sort made nests of resin, 

 attached to rocks and other objects. The former is the true 

 Anthidium; the latter is now known as the genus Dianthidium. 

 There are also structural differences; the easiest to see is the 

 little pad or pulvillus between the claws on the feet of Dianthi- 

 dium, absent in Anthidium. The genus Dianthidium is also 

 capable of subdivision, and I have separated as Anthidiellum a 

 group of small forms, existing both in Europe and America, in 

 which the hind edge of the scutellum is produced and sharp. 



(4) Osmia is a genus of Megachilid bees, in our fauna nearly 

 always blue or green. Some of the species have very brilliant 

 colors, others are quite dark. Colorado is especially rich in this 

 genus, 80 being recorded up to the present time. The anterior 

 wings, as in all Megachilidae, have only two cubital cells. Osmia 

 is being monographed by Miss Grace Sandhouse, who has ex- 

 amined many thousands of specimens for the purpose. Many of 

 the species have been described from one sex, and valuable work 

 can be done by any observer who will find the nests, and thereby 

 associate the sexes. It will doubtless then appear that in some 

 cases both sexes of a species have been described, but under 

 different names. Rather small bees more or less like Osmia and 

 Anthidium, but quite without a ventral scopa in the female, 

 belong to the parasitic genera Stelis and Chelynia. Mr. Chas. H. 

 Hicks has made observations which indicate, with little doubt, 

 that Chelynia monticola is parasitic in the nests of the brilliant 

 green Osmia fulgida. 



(5) Megachile includes the leaf-cutting bees, which often 

 damage rose bushes by cutting semi-circular pieces out of the leaves. 

 The bee does not eat these leaf-fragments, but uses them to build 

 its cells, in which the young will develop. The habit is a very 

 old one, for it not only may be observed on every continent, but 

 fossil in the Miocene shales at Florissant we found a leaf-cutting 

 bee (Megachile praedicta), and also a leaf cut in the characteristic 

 manner. The latter was figured in Nature, Feb. 10, 1910. Our 

 species of Megachile, of which there are 33, have the body surface 



