The Robber- Flies 



in the earth, and in decaying wood, and prey upon the larvae of 

 wood-boring beetles. In the ground they have been known to 

 feed upon the eggs of grasshoppers. Harris has described the 

 early stages of one species ( Asilus sertceus) which he thought 

 fed in the larval stage upon the roots of rhubarb. Harris was 

 seldom mistaken, but it is safe to say that as a rule the larvae are 

 carnivorous. The pupae are bristly, and have the head and the 

 segments of the abdomen provided with spines which assist them 

 in making their way out of the ground or the decaying logs 

 which they inhabit. 



The group is a very large one and comprises about three 

 thousand described species, of which four hundred or more in- 

 habit this country. The detailed life history of some robber-fly 

 is a great desideratum. 



143 



