The Osmiae 



paste made of some crushed leaf or other; 

 and none of them, except Latreille's Osmia, is 

 provided with the horned or tubercled armour 

 of the mud-kneaders. I should like to know 

 what plants are used in making the putty; 

 probably each species has its own preferences 

 and its little professional secrets; but hitherto 

 observation has taught me nothing concern- 

 ing these details. Whatever worker prepare 

 it, the putty is very much the same in appear- 

 ance. When fresh, it is always a clear dark- 

 green. Later, especially in the parts exposed 

 to the air, it changes, no doubt through fer- 

 mentation, to the colour of dead leaves, to 

 brown, to dull-yellow; and the leafy cha- 

 racter of its origin is no longer apparent. 

 But uniformity in the materials employed 

 must not lead us to believe in uniformity 

 in the lodging; on the contrary, this 

 lodging varies greatly with the different 

 species, though there is a marked predi- 

 lection in favour of empty shells. Thus 

 Latreille's Osmia, together with the Three- 

 horned Osmia, uses the spacious structures of 

 the Mason-bee of the Sheds; she likes the 

 magnificent cells of the Masked Anthophora; 

 and she is always ready to establish herself 



59 



