69 



emptied, but no traces of them were to be found, and it was 

 thought that they may have been devoured by the large 

 frogs which were discovered at the bottom (more probably 

 they perished from cold). The remaining lot of the imported 

 fish, sent to the Pongola Rubber Estate Company s property 

 in Zululand,.has also disappeared. 



It does not appear, therefore, from these experiments that 

 the West Indian " MilUons " can readily be acclimatised in 

 South Africa, and attention may now be profitably directed 

 to the finding of some native species of lish which may be 

 as useful in the extermination of the mosquito larvae. 



It is also to be borne in mind, as I have already stated 

 in a former report on the subject, that the introduction of 

 animals not native to the country has already been the means 

 directly or indirectly of injuring the native fauna, and this is an 

 additional reason for thoroughly testing the country's own 

 resources. 



A small fish known in some districts as " Kurper " 

 {Tilapia) has been observed (Howard) to clear the pools in 

 which it lives of mosquito larvae. It is a hardy little fish, 

 stands transportation well, and appears to multiply quickly 

 in favourable surroundings, so that further in\-estigations into 

 its habits may show that it can be utilized as a mosquito larvae 

 destroyer. A small species 7. plulaiulcr is abundant near 

 Pretoria, and a few years ago I conveyed a few in a large glass 

 vessel to Cape Town. They throve well at the Jonker's Hoek 

 hatchery, though not reproducing rapidlv, probably on 

 account of the colder water. Plate 111 ot this Report is 

 from a photograph of these fish in the living condition. 

 Fundulus melanospilus in German East Africa, Longo 

 Bay, Seychelles, and two other species from Longo 

 Bay and Zanzibar {F. guentheri) from Victoria Nyansa and 

 Lake Tschaia {F. taeniopygus) may prove useful. Species of 

 Haplochilus from Nyassa, Albert Nyansa, and probably in 

 many other regions, are also deserving of further investigation 

 in this connection. A small fish [Galaxias) found in the South 

 West of the Cape Province may prove a useful mosquito 

 ■destroyer though confined to the South Western districts of 

 the Cape Province. 



Some investigation in this direction has already been done 

 in India ; a number of fresh water cyprinodont fishes of 

 India and Burma have been kept under observation, and it 

 has been found that several species of Haplochilus in particular 

 are as hardy as "Millions " and devour mosquito larvae even 

 more readil3\ 



[C. P. 5-13.] 



