[By Thco. Curreras. 



The Fly thai causes Pellagra. 



According to Dr. S.iniboii, the disease pellagra is spread by a small black fly, whose lifc-historv is here shown. The eggs are laid in 

 streams, and the grnbs that liatch from them have the ren'iarkable form shown at the bottom of the picture. Thcv are attached by 

 their broad, hinder ends to weeds or stones, and their heads are funiished with a couple of fringed lobes with which they sweep 

 microscopic food to the montli. The figures attached to weed abov<- them arc the chrysalids in their open cocoons. The fly is seen 

 above the water. .Ml the ligures are considerably enlarged. 



