262 



J. M. DALZIEL. 



Table V. 



Species of Mosquito. 



Number of Occasions. 



Percentage. 



CuJiciomyia nebuhsa . . 

 Stegomyia fasciata 

 AiwpJieJes costalis 

 Culex decens 

 „ tigripes . . 



396 



51 



2 



1 



1 



88 

 11 



1 



Culex tigripes occurred in association with both C. nebuhsa, and S. fasciata. 

 S. fasciata occurs either alone or more often in association with C. nebuhsa,. 

 but the latter, apart from its preponderance in number of finds, undoubtedly 

 furnishes immeasurably more imagines from this particular source than the former. 

 This mosquito is exceedingly common in native houses and probably at present 

 greatly exceeds S. fasciata in numbers (see below). Although a considerable 

 number of ordinary water-pots are concealed or placed in locked rooms during 

 the inspector's visit, there can be no doubt that the weekly inspection of premises 

 is successful in detecting by far the greater number of domestic receptacles which 

 contain Stegomyia larvae, and thus disposing of large numbers of this species in 

 its earlier stages. In addition to the agbo pot, apparently its most prolific source, 

 C. nebuhsa has been bred from samples obtained from the following : — catchpits 

 (for collecting household suUage), drains, water-pots, barrels, tins, a lawn-mower, 

 roof-gutters, wells, pools, crab-holes, canoes, dung-emulsion (for smearing floors), 

 tanning extract, starch emulsion, bottles Ol palm-wine, and tree-holes. It will 

 be noticed that several of these are of the nature of fluids rich in organic matter, 

 in which, as in agbo particularly, the Psychodid, Pericoma yneridionalis, Eaton, is 

 its extremely abundant and almost constant associate. It may be added that 

 C. nebuhsa is by no means uncommon in pools away from dwellings, often in 

 association with 0. irritans and A. costalis, so that domesticity, though a prominent 

 feature of its bionomics in Lagos, is not an essential characteristic. 



rviosquitos breeding in Roof-gutters. 



Previous to their gradual removal after installation of a pipe-borne water-supply, 

 roof-gutters were fairly regularly inspected and swept. Comparatively few samples 

 have been examined, with the following record : — 



Table VI. 



Species of Mosquito. 



Number of Occasions. 



Percentage. 



Stegomyia fasciata 



„ luteocephala 

 Ochlerotatus irritans . . 

 Culiciomyia nehuJosa 

 Anopheles costalis 



„ mauritianus 



13 



4 



2 -^ 



2 



1 



1 J 



56-5 

 17-4 



26-1 



