natural, history

•DISCUSSIONAedes alboli"eatus, Culex halifaxi and C. (Lophoceraomyia) sp. were previously unknownfrom Bellona, and A. albolineatus, C. annulirostris and C. squamosus had notbeen collected on Rennell. Five of the eight species of mosquitoes now known from thetwo islands - Anopheles jarauti, Aedes albolineatus. Culex halifaxi. C. allnulirostrisand C. squamosus - are common to New Guinea (BICK, 1951) and Guadalcanal,British Solomon Islands Protectorate (BELKIN, 1945). A. albilabris is restricted to theSolomons, and A. s. scutellaris, which occurs in New Guinea and the New Hebrides.is not known from the Solomon Islands north of Rennell and Bellona. MARKS (1954)quoted HALE-CARPENTER for the information that Rennellese butterflies of the genusEuploea differ considerably from those of other islands of the Solomons. the evidenceindicating that at least some of the insect fauna of Rennell was derived from thecastern tip of New Guinea via the louisiade Archipelago. She drew attention to thedesirability of confirming earlier records of A. s. scutellaris from Rennell. and hassince (p. c .. 1954) examined males from the present collection and established thatthey are definitely referable to this species. Two of the other mosquitoes of the island,All. jarauti and C. alll1u/iroslris. are also found in the New Hebrides and NewGuinea but occur elsewhere in the Solomons as well. while "Culex hilli huxtolli" istisfed from both the latter Group and the New Hebrides. The last three records thus"add nothing to the theory that Rennell and Bellona have acted as stepping stonesbetween New Guinea and the New Hebrides.1t is true that three of the four mosquitoes not found in the New Hebrides (A. albalineatus,C. halifaxi and C. SqIlQI1l0SIIS) might have reached Rennell equally easilyfrom eastern New Guinca or the Solomons proper. but A. albilabris could only havecome from an island of the l;;tter group. However. human agency may well ha,'ebrought about the southward dispersal of this container-breeding species. lanae ofwhich common Iv occur in coconut husks and c,'en in brackish water at thebottom of canoes (c. g., station nO. 238). Such habits obviously favour accidentaltransportation, and the Rennellese have a tradition of inter-island \ oyaging(FIRTH, 1931).LAMBERT (1949). having quoted evidence that malaria had been introduced intoRennell between 1933 and 1937. feIt it necessary to assume that "As trading vesselswere prohibited. a government or mission vessel may have carried anophelines" tothe island. Such an assumption is only required if LAMBERT'S failure to find anophelinesthere in 1930 or 1933 is regarded as proof positive of the absence of thesemm'luitoes at that time. It is of course quite possible that anophelism withoutmalaria prevailed on this isolated island until parasite introductions took place inthe early nineteen-thirties. and that LAMBERT simply o\erlooked the occurrence ofanophelines. This is the more likely in that BLACK (J 952) made a prolonged searchbefore finding his only larval habitat for Anopheles jarauti (at Niupani. betw~cn thegrassy margin of the lake and a moored canoe): while during the nresent suney,despite the fact that malaria proved rife at Lavanggu. a three-hour search in thevillage and its vicinity yielded neither adult nor larval anophelines, and only a single229