402 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



HOUR OF DAY 



Fig. 15. — Relation of time of day to biting activity of the three principal 

 anthropophiHc species of Simuliidae. (Prepared on 3-cycle semilogarithmic 

 paper.) The flies were collected while feeding on human subjects who were 

 exposed to bites on 95 days from 6 : 30 a.m. until 5 : 30 p.m. Flies biting on 

 regions exposed to sun or to shade have been grouped together. 



