FABRE'S BOOK OF INSECTS 



outer cells, the Osmia comes in and takes possession of 

 them. She divides the corridors into unequal and in- 

 artistic cells by means of rough earthen partitions, her 

 only idea of masonry. 



The cells of the Anthophora are faultlessly regular and 

 perfectly finished. They 'are works of art, cut out of 

 the very substance of the earth, well out of reach of all 

 ordinary enemies; and for this reason the larva of this 

 Bee has no means of spinning a cocoon. It lies naked 

 in the cell, whose inner surface is polished like stucco. 



In the Osmia's cells, however, means of defence are 

 required, because they are at the surface of the soil, are 

 roughly made, and are badly protected by their thin par- 

 titions. So the Osmia's grubs enclose themselves in a 

 very strong cocoon, which preserves them both from the 

 rough sides of their shapeless cells and from the jaws 

 of various enemies who prowl about the galleries. It 

 is easy, then, in a bank inhabited by these two Bees, 

 to recognise the cells belonging to each. The An- 

 thophora's cells contain a naked grub : those of the Osmia 

 contain a grub enclosed in a cocoon. 



Now each of these two Bees has its own especial 

 parasite, or uninvited guest. The parasite of the Osmia 

 is the black-and-white Fly who is to be seen so often 

 at the entrance to the galleries, intent on laying her eggs 

 within them. The parasite of the Anthophora is the 



[160] 



