Larval Dimorphism 



walls, the slopes and the sand, sometimes In 

 small platoons, most often singly. I can ex- 

 pect nothing of those vagabonds, who are here 

 to-day and gone to-morrow, for I know 

 nothing of their settlements. To keep a watch 

 on them, one by one, In the blazing heat, is 

 very painful and very unfruitful, as the swift- 

 winged insect has a habit of disappearing one 

 knows not whither just when a prospect of 

 capturing its secret begins to offer. I have 

 wasted many a patient hour at this pursuit, 

 without the least result. 



There might be some chance of success 

 with Anthrax-flies whose home was known to 

 us beforehand, especially If Insects of the same 

 species formed a pretty numerous colony. The 

 enquiries begun with one would be continued 

 with a second and with more, until a complete 

 verdict was forthcoming. Now, In the course 

 of my long entomological career, I have met 

 with but two species of Anthrax that fulfilled 

 this condition and were to be found regu- 

 larly: one at Carpentras; the other at Serig- 

 nan. The first. Anthrax sinuata, Fallen, 

 lives in the cocoons of Osmia tricornis, who 

 herself builds her nest In the old galleries of 

 the Hairy-footed Anthophora; the second, 

 Anthrax trifasciata, Meigen, exploits the 

 8i 



