26 MOSQUITO WORK IN KHARTOUM, ETC.
conditions. I append the average maximum and minimum temperatures, and the average wind velocity recorded during August, September and October, these being the meteorological factors likely to affect the mosquitoes in the work of
Influence of
propagating themselves.
Average maximum Average minimum Wind velocity in
meteorological 1903. in °C. in QC. miles per hour. conditions August. . . . . . 37-45 24-25 2-7
September . . 38-5 20*88 2-10
October . . . . .38-51 22-82 1-98 It will 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 No. 3. This map is drawn up on slightly different lines, as it was deemed inadvisable to repeatedly spot all the uninfected water collections previously shown. Only new water collections and infected places are marked. It will be noticed that during this month pools began to make their appearance on the river’s bank and on a sandbank which had formed 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 during the last two months of 1903 and the first month of 1904 are here stated :—
Average maximum Average minimum Wind velocity in
m JC.
37*28 35
in °C. 20-89 18*01
miles per hour
1-48 1-75
1903
November December
1904 January . 31*5 16*3 1’82 I do not think these conditions influenced the mosquitoes to any marked extent.
Statistics The general figures work out as follows:
During Aug. During Oct. During Jan.
after treatment
and part of after treatment. Sept, before
treatment
Several destroyed Total water collections . . . 670 664 689 Total infected . . . 324 163 102 > Percentage infected . 50 24-5 14-8 Harbouring Culex (total Culex) . . 321 161 100 „ Culex and Anophelina 12 2 1 „ 1; Anophelina alone . . 2 1 1 „ Culex and Stegomyia 1 0 0 „ Stegomyia alone . . 1 1 1 Total Anophelina. 14 3 2 Total Stegomyia . 2 1 1