CRAB-HOLES, TREES, AND OTHER MOSQUITO SOURCES IN LAGOS. 



263 



The occurrence of the larvae of A. mauritianus, Grandpre, is unique in the present 

 record. It is a very rare mosquito in Lagos, but the adults have been found at least 

 once in the same locality, viz., the dwellings around the Golf-course. The larvae 

 have previously been obtained at Yaba (which is within the municipal area) in a 

 pond near the Research Institute, and in road puddles in the wet season. 



Mosquitos from various Domestic Sources. 



The weekly visit of the Sanitary Inspector has made it possible to obtain samples 

 of mosquito larvae from domestic sources, and these have been collected whenever 

 circumstances permitted of their examination at the Research Institute with a view 

 to determination of the species. The following record is the result of material 

 thus brought under observation during an aggregate of 45 months, between the 

 years 1914 and 1918, thus : — 1914, May to November, 7 months ; 1915, 12 months ; 

 1916, January to April, and November to December, 6 months ; 1917, 12 months ; 

 1918 January to August, 8 months. Amongst domestic receptacles are included 

 for the present purpose, besides the usual utensils such as water or agbo pots, tins, 

 bottles, tanks, barrels, etc. , the following : — wells on the premises, roof -gutters, 

 house- drains and catch-pits, but not puddles in the yard or crab-holes. 



No less than 17 species are represented, while the total number of species captured 

 in Lagos during the period of the present record is 46. It may also be accepted 

 that a collection under similar circumstances in any large coast town in West Africa 

 will furnish a like preponderance of S. fasciata in greater or less degree ; e.g. , in 

 Bathurst (date ?) with a collection obtained from 150 compounds each month, 

 the proportions were Stegomyia 94 per cent., Culex 5 '5 per cent., Anopheles 0' 5 per 

 cent. 



During two years in Accra, 1,121 domestic samples examined gave the following 

 result (Ingram, Bull. Ent. Res. x, 1919, pp. 50-51) : — 



S. fasciata occurred in 876 or 

 C.fatigans ,, ,, 221,, 



A. costalis ,, „ 43 ,, 

 C, decens „ ,, 20 „ 



C. invidiosiis „ ,, 18 ,, 

 C. duttoni „ ,, 5 ,, 



C. tigripes Yai. fuscus 3 ,, 

 C. nebulosa ,, ,, 1 ,, 

 A collection in Lagos similar to the present one, composed of 1,043 samples and 

 covering 8 months in 1910-1911, was recorded by Graham (Bull. Ent. Res. ii, 

 p. 127) as below : — 



S. fasciata in 92 '5 per cent, of domestic water-samples examined. 



Pectinopalpus fuscics* „ 21*6 ,, „ 



C. duttoni ,, 8 "3 ,, „ 



C. tigripes vax. fuscus ,, 5*3 ,, ,, 



C. nigrocostalis * „ 1*8 ,. ,, 



Pyretophorus costalis „ 1-8 ,, „ 



78*0 per cent. 

 19-7 



3-0 



1-7 



1-6 



0-4 



0-2 



0-08 



* Pectinopalpus fuscus, Theo.=Culiciomyia nebulosa, Theo. 

 Th.eo.=Culex decens, Theo. 



and Culex nigrocostalis 



