Larval Dimorphism 



coloured pupa, or even in that of the full- 

 grown insect. The Osmia, still more precoc- 

 ious, though dating from the same period, 

 shows herself exclusively in the adult form, a 

 bad omen for my investigations, for what the 

 Anthrax demands is the larva and not the 

 perfect insect. The Fly's grub doubles my ap- 

 prehensions. Its development is complete, the 

 larva on which it feeds is consumed, perhaps 

 several weeks ago. I no longer doubt but 

 that I have come too late to see what happens 

 in the Osmia's cocoons. 



Is the game lost ? Not yet. My notes con- 

 tain evidence of Anthrax-flies hatching in the 

 latter half of September. Besides, those 

 whom I now see exploring the rock are not 

 there to take exercise : their preoccupation is 

 the settling of the family. These belated ones 

 cannot tackle the Osmia, who, with her firm, 

 adult flesh, would not suit the nurseling's 

 delicate needs and who, moreover, powerful 

 as she is, would offer resistance. But in aut- 

 umn a less numerous colony of honey-gather- 

 ers takes the place, upon the slope, of the 

 spring colony, from which it differs in species. 

 In particular, I see the Diadem Anthidium* 



^A Clothier-bee, who lines her nest with wool and 

 cotton. — Translator's Note. 



89 



