58 



Much work has been done on the breeding of Anophehnes in 

 the laboratory, when it was hoped to settle such problems as the 

 relative status of A. suhpictus, Grassi {rossi, Giles) and A. vagus, Don. 

 {rossi var. indefinitus, Ludl.), that of A. hyrcamis and its var. 

 peditaeniatus, the relationship, if any, between A. maculatus and 

 A . karwari, and various other points. This investigation has afforded 

 much information, and, so far as is known, is the first attempt to 

 demonstrate in Anophelines (by the unassailable proof obtained by 

 breeding) the inheritance of minute variations, which has been proved 

 to occur in the case of other insects. A study was made of different 

 larvae in various alga-containing media, and it was ascertained that 

 A . maculatus and A . karwari have a predilection for certain filamentous 

 algae, particularly a species of Spirogyra. All species, except jungle 

 ones, thrive in the laboratory on a species of flagellate protozoon, 

 Euglena viridis, and A. hyrcanus and A. barbirostris can thrive on a 

 species of Volvox when it is immature and small enough for their 

 consumption. The only jungle species that thrived on E. viridis 

 was A. leucosphyrus. 



A study of the seasonal prevalence of algae was commenced, and 

 attempts made to obtain laboratory cultures, but with little success 

 owing to the limited knowledge of these organisms. A small unicellular 

 alga isolated from a small muddy pool throve luxuriantly in a medium 

 of thoroughly decomposed rice water and similar subcultures. On 

 this A. vagus was bred from egg to adult ; a similar attempt with 

 A. maculatus was unsuccessful, though a few larvae attained half- 

 growth very slowly. 



Records as to the seasonal prevalence of Anophelines show that 

 A. vagus oviposited month by month from March onward, and that 

 A. maculatus only failed to do so in September. It was found that 

 owing to the drying up of pools during a season of drought in July, 

 larvae of A. vagus, in the absence of the favoured breeding places, 

 increased largely during the earlier rains in fish ponds, where they 

 usually occur sparingly. Though Aedes argenteus {Stegomyia fasciata) 

 has been reported as the prevalent species in the vicinity of Kuala 

 Lumpur, in no instance was it captured or bred from among a total 

 of 3,850 mixed Culicid larvae obtained, which were mainly Aedes 

 (S.) albopictus. 



Further investigations were made on the habits of a species of 

 Ceratopogon, a midge that attacks Anophelines. It breeds in small 

 muddy pools, from which pupae have been obtained. The midges 

 have been found attached to the abdomen of their host, with the object 

 of depriving them of their meal rather than obtaining the juices from 

 them. 



The discovery of a Protozoon in the gills of the larvae of Aedes (5.) 

 albopictus has already been noticed [R.A.E., B, ix, 190]. A study 

 of the factors influencing larval coloration was made, particularly 

 in the case of Anopheles hyrcanus. The possible transmission of 

 malaria from an infected mosquito to its offspring was investigated 

 in the case of A. maculatus with negative results. Biting experiments 

 are still being made with A. aconitus, A. barbirostris, A. hyrcanus, 

 A. ludlowi and A. fuliginosus. Local outbreaks of malaria were 

 investigated with the object of testing the continued efficiency of 

 drainage schemes, and some ravines were drained and examined as 

 to the presence of breeding places. 



