DOMESTIC MOSQUITOS OF NIGERIA. 327 



The new species, A. domicolus, was described by Mr. F. W. Edwards (Bull. Ent. 

 Res. vi, p. 363) from specimens caught in my house at Zungeru, and I have since 

 obtained it at Kaduna Junction. 



3. Stegomyia group. 



Stegomyia formed only 0-2 per cent, of all mosquitos obtained. This is largely 

 due to active measures of sanitation, as Stegomyia fasciata swarms in neglected 

 stations. It is an interesting fact that although Stegomyia vittata (sugens) breeds 

 by thousands in rocky holes filled with clear water in the river beds at Kaduna 

 and Zungeru during low water, I have never caught this mosquito in my house, 

 and have only once obtained its larvae from a domestic water-pot. A further 

 point of interest is that although I frequently obtained the larvae of Stegomyia 

 unilineata — the African representative of the Oriental Stegomyia variegata (scutel- 

 laris) — from hollow trees at Kaduna, I never obtained this mosquito in my house. 

 The presence of S. unilineata should, however, be remembered in view of the fact 

 that yellow fever has occurred at Kaduna. 



4. Culex group. 



The species of Culex are most numerous during the hot dry season before the rains 

 and during the early rains. Culex decens and C. invidiosus formed an overwhelming 

 majority of the Culicines caught in my house. Thus of 1,277 Culicines examined 

 these two species together formed 1,133 or 88'8 per cent, of the total obtained. 

 Culex dutloni, which is a common domestic mosquito in Nigeria, N.P., does not 

 form a high proportion of the Culex obtained, probably for the same reason that 

 the Stegomyia figure is so low. In Northern Nigerian stations closely surrounded 

 by marsh Mansonioides uniformis forms a high percentage of this group as a domestic 

 pest. 



5. Seasonal Variation. 



The seasonal variation of Anopheles and Culex during one year is shown in a 

 graph (fig. 1) taken from Table I. The figures are lowest in January, during the 

 dry season when the cold dry " harmattan " wind is blowing and the nights are 

 cold. There is an immediate rise on the cessation of the harmattan wind (February 

 on the graph), which is maintained during the hot dry weather preceding the rams. 

 Early heavy rains cause a fall in the numbers obtained (May to July on the graph), 

 but during the steady rains of August the figure rises rapidly, reaching a maximum 

 in October, the month after cessation of the rains. The commencement of the 

 cold " harmattan " wind in early November causes an immediate large fall in the 

 numbers obtained, and the numbers steadily decrease during the cold dry months 

 of December and January. 



6. Relative Domesticity of various Species. 



To form some idea of the real mosquito pests to man I think there is some value 

 in obtaining the adult mosquitos caught in a house over a prolonged period. A 

 totally false idea is obtained from a " larval or mosquito survey " of a station, 



