196 
Malaria in Malaya 
III. Practical importance of the larval habitat. 
It is evident that this study possesses a more than academic importance. 
Let us imagine the effect which would be caused by an apparently unimportant 
change in the habitat of such a species as M. ludlowi, which we may suppose 
to acquire the breeding habits of M. indefinita. Such an occurrence in the 
Malay Archipelago would spell disaster. The severe endemic malaria, at 
present confined to the sea coast, and strictly localized in the interior, would 
lead to the spread of the disease over wide areas in a manner corresponding 
to what is seen in some parts of Africa. All this would result from an exchange 
of habitat between two Anophelines, so closely allied morphologically that 
some entomologists refuse to consider them as distinct species. Moreover, the 
eradication of the larvae would become a practical impossibility; for an 
Anopheline capable of breeding in all possible collections of water, in a 
country of high humidity and heavy rainfall, and where the population is 
dependent on the cultivation of rice, cannot be abolished. 
Although conditions in the Malay Archipelago are not so bad as this, still 
the prospects are not uniformly favourable, even if our purpose aims, not at 
the complete suppression of malaria, but only at checking the more severe 
endemic and epidemic manifestations. We have in that case to exterminate 
only M. ludlowi, M. aconita, N. maculatus, perhaps S. aitkenii, and in some 
places perhaps N. leucosphyra and M. umbrosus. It will simplify our task 
considerably, provided these species are restricted in their breeding-places, 
otherwise we may as well commence our operations against all local Ano¬ 
phelines, excepting only the breeding-places peculiar to M. indefinita, C. kochii 
and N. punctulata (tesselata). 
This, unfortunately, is the attitude which we have to take with regard to 
M. aconita and N. maculatus. For reasons mentioned above, specific sanitation 
cannot be put into operation. Even if in a certain district, one of these species 
seems to be limited to one type of breeding-place, still we cannot advise the 
exclusive abolition of the larva, because observations from other localities 
have taught us that it may readily take to another kind of breeding ground. 
Nevertheless the study of the breeding habits of these mosquitoes has given 
us some useful knowledge. We have often observed careless cultivation of 
the rice-fields bv the natives; the fields are inundated before being sown, in 
order to simplify the operation of ploughing; after harvesting, the water is 
not allowed to drain off, and, in consequence, the rice-fields are converted 
into swamps. Fields are frequently seen, in which the rice-stalks lie down in 
the water, because the owner of the field neglected to cut the ears in time. 
Such rice-fields constitute favourable breeding places for many species of 
Anophelines, among them M. aconita and N. maculatus. This negligence is 
harmful, not only from the sanitary standpoint, but also for agricultural 
reasons, and the latter reason alone should help to bring about an improve¬ 
ment. 
