THE DOMESTIC MOSQUITOS OF ACCRA, 171 



harbouring these larvae in February, and suggests that possibly this " was caused by 

 the absence of suitable puddles or pools at the end of the dry season." 



In the second map (Map II.) all the samples of larvae that were collected in native 

 compounds during a complete year, 1915, so far as it was possible to locate them, are 

 shown in full, so as to give some idea of both their actual numerical and specific 

 distribution. Each conventional sign indicates one sample containing larvae of the 

 particular species shown, and the signs in each block are distributed evenly, as it was 

 not possible to localise the compounds accurately. 



A Comparison of the Adult Mosquitos collected at Accra with the Larvae found 

 breeding in the Compounds. 



A large number of different species of mosquitos have been collected at Accra. 

 According to the pamphlet entitled " Distribution of Mosquitos in West Africa," 

 which was printed for the Yellow Fever (West Africa) Commission in August 1913, 

 no less than thirty-one species had been recorded up to that time, and to these the 

 collections made by us in 1915 added nine new names, bringing the total up to forty- 

 one. These species were Anopheles costalis, A. funestu^, A. pharoensis, A. umhrosm, 

 Culex decens, C. duttoni, C.fatigans, C. grahami, C. guiarti, C. insignis, C. invidiosus, 

 C. ornatothomcis, C. quusigelidus, C. thalassius, C. thalassius var. fusciis, C. tigripes, 

 C. tigripes var. fusca, Culiciomyia nebidosa, Cyathomyia (Protomelanoconion) fusea, 

 Mansonioides africamis, M. uniformis, Micraedes inconspicuosu-s, Mucidus mucidiis, 

 Ochlerotatus albocephalus, 0. irritans, 0. doniesticus, 0. minulus, 0. minutus var. 

 bianmdatus, 0. minutus var. stenoscutus, 0. minutus var. tarsalis, 0. nigrocepJuilus, 

 0. punctothoracis, Stegomyia fasciata, S. luteocephala, S. metallica,, S. unilineata, 

 Uranotaenia balfouri, U. connali, U. mashonxiensis, U. mMtjeri. Formidable as is this 

 list, it is nevertheless incomplete, as we have found by the examination of some 

 specimens collected recently. It is somewhat remarkable that of all these mosquitos 

 known to occur at Accra only ten were represented in the samples of larvae from 

 compounds sent for examination by the Medical Officer of Health. 



Graham in his paper referred to above speaks of " The superior accuracy and 

 finality obtained by dealing with the larvae breeding in the native yards " and states 

 that by employing " this method of ascertaining the mosquito fauna of a native town 

 . . . the results have proved more accurate and complete than those obtained by other 

 methods." Whilst agreeing with him that " The catching of mosquitos in native 

 yards and houses is difficult, and offers none of the advantages gained by dealing with 

 the larvae," we cannot support his statements as to the accuracy and finality of the 

 method in view of our experiences at Accra. It may be pointed out too that Graham's 

 own study of the larvae found in domestic vessels revealed the presence of only six 

 species (see above) at Lagos, although, quoting again from the pamphlet printed for 

 the Yellow Fever Commission, forty-one species have been recorded as occurring in 

 this town, namely, Anopheles costalis, A. funestus, A. mmiriiianus, A. pJiaroensis, 

 A. umbrosus, Aedomyia catastida, Banksinella lineaiopennis {luteolateraUs), B. pxncio- 

 costalis, Culex consimilis, C. decens, C. duitoni, C. grahami, C. insignis, C. inridiosu-s, 

 C. quasigelidus, C. rima, C. thalassius, C. tigripes var.fmca, C. univittatu^, Cidiciomyia 

 nebidosa, Eretmopodiles inornatus, Mansonioides africanus, M. uniformis, Micra-edes 

 inconspicuosus, Mimomyia mimomyiaformis, Ochlerotatus caliginosus, 0. domesticu-s, 



