252 J. M. DALZIEL. 



Stegomyia fasciata and Anopheles costalis tie for the 5tli place, but with two 

 important distinctions, viz. (1) the occurrence of Stegomyia larvae has shown no 

 regularity in number or in season of year, while Anopheles larvae have been found 

 in crab-holes only in the period June to October ; (2) the localities of the respective 

 sources (as recorded with each sample) have indicated for Stegomyia either the 

 compound of a dwelling house (European or native) or a place in comparatively 

 close proximity ; in a few instances the Golf-course swamp is indicated, of which 

 probably no part is much more than 200 to 300 yards from dweUings of some sort ; 

 in the case of Anopheles the nature of the recorded notes, e.g., "in crab-holes full 

 of rain-water," " along with tadpoles, etc.," indicate along with the stated localities 

 either a temporary meteorological condition or a permanent comparatively water- 

 logged site as a constant accompanying factor. In many cases Anopheline larvae, 

 often visible within the hole at a depth of a few inches, may have arrived there 

 with the retreat of the water from the surface pool or swamp on which the eggs 

 were laid. 



Culex insignis furnished about 5 per cent, of the recorded finds, but occurred in 

 small actual numbers. No special seasonal incidence is suggested, and although it 

 has been found in dwelling-houses, and perhaps oftener in out-houses, it is not a 

 particularly domestic species. 



Culiciomyia nehulosa shares with S. fasciata the distinction of being the most 

 domesticated of the mosquitos ; indeed, its preponderance in organically polluted 

 water or vegetable infusions in households probably gives it precedence in this respect 

 in Lagos. Its occurrence in crab-holes is thus, as would be expected, less frequent, 

 and generally in occupied compounds, though it has also been found in the Golf-course 

 swamp. 



Of the remaining species in the above list one may say that C. thalassius as a lover 

 of brackish water, though not dependent on it, is hkely to be a more common 

 inhabitant than here indicated of crab-holes in locahties where this condition prevails, 

 e.^.,the tidal swamps at certain places on the island or neighbouring mainland at 

 such a distance from the inhabited areas as to be beyond the radius of our special 

 work. The species is common in houses in the vicinity of and to leeward of its 

 breeding places, and bites freely. C. rima occurred in the vicinity of the Golf-course, 

 and its adults were found in European houses, stables, etc., of the same locality, 

 but no other breeding place has been observed. 



The 4 species at the end of the list are apparently exceptional. The larvae of 

 S. luteocephala were associated in the crab-hole with those of S. fasciata and 

 C. nebulosa, while about the same date the larvae of the first-named were found in the 

 fork of a tree in the same European compound. Adults have been taken occasionally 

 in houses of the neighbourhood. Those of C. salisburiensis have been found several 

 times in surface pools, and the imagines at least once in a house of the same locality. 

 No other source of the larvae of M. inconspicuosus and U. hilineata var. fraseri 

 has come to notice ; imagines of the former have not been captured, but those of 

 the latter have at times shown a localised prevalence and at one time abounded in 

 in the rooms of Government House itself. The occurrence of more than one species 

 of larva in one crab-hole is common, and in fact perhaps almost usual. The two 



