24 



MOSQIITO WDUK IX KIIAUTOUM, ETC. 



Distribution 

 of genera 

 in Khartcjuni 



Reinfection by 

 steamer bred 

 mosquitoes 



Mosquito 

 Maps 



Ava-s fouud to be liniitod. 

 reudered necessary by the 



Cnlex fatujanf is ubi(jiiitt)us, but is chiefly, as has long been known, a domestic 

 variety. It is the wi'll mosquito par excellence, and consequently is found all 

 over Khartoum, from the steamers back to the cemetery and Gordon's old 

 ramparts, and from the British barracks in the east to the Zoological Gardens 

 in the Avest. It also loves river pot)ls, garden tanks, and bath-Avaste pits, and 

 Avill breed in almost any kind of dirty Avater, even in that streaked Avith oil, 

 as found in steamer engine rooms. 



Pi/retophorus contalis, on the other hand, is not domestic, and its range 



It chiefly occurred in the various Avater collections 

 rrigation of the Palace Gardens. It Avas found in 

 those Avhich Avere not stocked Avith fish, and especially in valve pits and shaUoA^--, 

 reedy pools. It seemed indiffei-ent to the presence of frogs. This mosquito has 

 also been found in garden tanks along the river fi'ont, in the pools left by the 

 falling Nile, in the sakia pits of the Gordon Gardens, and in a fcAv, a Aery fcAV, 

 Avells. It Avas pi-esent in considerable nmnbers in the Palace Gardens, and 

 infested tlie neighbouring houses, but it does not appear to fly far fi'om the 

 shelter of vegetation, nor has it ever been found breeding on board steamers at 

 Khartomn, partly because it is someAvhat fastidious in its tastes, and prefei*s 

 natm'al collections, and partly because the larva? require plenty of light. 



Stegoiiiyia fasciata again, is the great steamer mosquito, and has not been found 

 to breed much in Khartoum itself. It is to be remembered, hoAvever, that the larvffi 

 of this genus differ someAvhat in habits from those of the other genera. They are 

 more Avorm-like, hug the bottom and come only infi-equently to the surface, 

 consequently they may have been more often missed. It has been found breeding 

 in the zeers and a feAv other Avater collections, but very rarely in the AveUs. 

 Further, and this is interesting, it seemed to be almost AvhoUy confined to Avhat may 

 be called the front belt of the toAvn, the river zone, and hence my belief that it Avas 

 very largely an unAvelcome gift from the steamers. Certain Avells, opposite Avhich 

 steamers Avcre accustomed to lie up, for example at the post office, (see page 19) 

 constantly became reinfected Avith Culex after they had been treated and fi'eed, and 

 these also I believe came from the boats. Indeed it has been found much easier 

 to keep the south part of the toAvn free than that Avhich borders the Blue Nile. 



The accompanying maps shoAV the respectiA'c distribution, and also exhibit 

 another point, the effect of the treatment. 



Map No. 1 represents the condition of the A'arious Avater collections as found 

 during the first complete round of the toA\Ti made in iVugust and the first jiart of 

 September, 1903. 



Map Nt). 2 sheAvs the same collections and any neAv ones Avhich may have been 

 discovered or been formed (for ncAV Avells are constantly being sunk), after the 

 necessary oilings. Different marks have been devised to explain different conditions 

 so that the improvement Avhich has resulted may be seen at a glance. The second 

 maji brings us doAvn to the end of the sunnner (October 31st) and the summer 

 Avork, thus excluding any fallacies Avhich niight arise from altered climatic 



