w 2 



<I3 IS 10 17 18 21 2} 29 27 29 31 39 3S> 



TEMPERATURE (DEGREES CENTIORAOE) 



Fig. i8. — Efifect of air temperature on biting activity of Shnulium (L.) cal- 

 lidiim. (Prepared on 4-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. The air temperature was recorded every 10 minutes. 

 Sun or shade readings indicate that the flies were biting on a part of the body 

 that was exposed to either the sun or shade. 



o 



z 



58 



tc 

 u 

 a 



z 

 g 



< 

 > 



a. 



bJ 

 (0 



o 

 o 



9M00 81-90 



71-80 



61-70 



51-60 



41-50 



31-40 



RANGE OF RELATIVE HUMIDITY 



Fig. 19. — Effect of relative humidity on biting activity of Simulium (S.) 

 ochraceum. (Prepared on 3-cycle semilogarithmic paper.) The flies were col- 

 lected while feeding on human subjects who were exposed to bites on 69 days 

 from 6 : 30 a.m. until 5 : 30 p.m. Relative humidity was recorded every 30 min- 

 utes. Sun or shade readings indicate that the flies were biting on a part of the 

 body that was either shaded or exposed to the sun. 



404 



