Fresh-Water Insects 293 



more perfectly adapted to life in the water. The grub 



F'iG. 160. — a. Larva of SimuJium ornatuiii, IVIg., from side; h. 

 from below ; c. pupa, from front ; d. from behind, magnified 

 7 times ; e. pupa case, magnified 4 times. From Osborn 

 (after Verdat), Bull. 5 (n.s.),"Div. Ent. U.S. Dept. Agr. 



of the Gnat or the Drone-fly needs to rise to the sur- 



