Influence of 



meteorological 



conditions 



Statistics 



26 MOSQUITO WORK IN KHARTOUM, ETC. 



conditions. I append the average maximum and minimum temperatures, and 

 the average wind velocity recorded dui-ing August, September and October, these 

 ]>eing the meteorological factors likely to affect the mosquitoes in the work of 

 propagating themselves. 



,„„„ Average niaximiim Average miuimum Wind velocity iu 



in °C. iu ''C. miles per hour. 



August 37-45 24-25 2-7 



September . . 38-5 20-88 2-10 



October .... 38-51 22-82 1-98 



It wiU be seen that the weather conditions differed very slightly in September 

 and October. 



The work was steadily continued during November and December, and a 

 record of the conditions found during January is exhibited in Map Xo. 3. This 

 map is drawn up on sUghtly different hues, as it was deemed inadvisable to 

 repeatedly spot aU the uninfected water collections previously shoAvn. Only new 

 water collections and infected places are marked. It Avill be noticed that dui-ing 

 this month pools began to make their appearance on the river's bank and on a 

 sandbank which had foi'med and stretched out into the main stream. Such pools, 

 provided they were large enough, were speedily occupied, despite the fact that they 

 were often exposed to the strong north wind. 



The meteorological conditions prevalent dui'ing the last two months of 1903 



and the first month of 1904 are here stated : — 



■.nno Average maximum Average minimum Wind velocity in 



^■^^ in "C. in °C. miles per hour 



November .... 37-28 20-89 1-48 



December 35 18-01 1-75 



1904 



January 31-5 16-3 1-82 



I do not think these conditions influenced the mosquitoes to any marked 

 extent. 



The general figures work out as follows : — 



During Aug. During Oct. d^^.^^„ j^n 

 and part of after treatment. aft'o,- 



Sept. before Several treatment 



treatment destroyed 



Total water coUections 670 664 689 



Total infected 324 163 102 



Percentage infected 50 24-5 14-8 



Harbouring Culex (total Culex) . . 321 161 lOO 



„ Culex and iVnophelina 12 2 1 



„ AnopheUna alone .... 2 1 1 



„ Culex and Stegomyia 10 



„ Stegomyia alone .... 1 1 1 



Total Anophelina 14 3 2 



Total Stegomyia 2 1 1 



