239 The Philippine Journal of Science 1915 
It is true that A. febrifer was found breeding near towns 
with little or no indigenous malaria, but the breeding places 
were in most cases more or less remote from the majority of 
the houses or comparatively few larvee were found in them. 
The lack of gamete carriers might in some cases account for 
the lack of malaria in these localities. However, none of the 
localities surveyed were found nonmalarious where A. febrifer 
bred abundantly near houses and had unobstructed flight to 
them. Possible exceptions are Bolhoon, Cebu, and some more 
or less recently established barrios on large plantations. Many 
factors are concerned in the transmission of malaria, and as 
investigations in many localities of other countries have shown, 
the juxtaposition of mosquito malaria carriers and of population 
is not necessarily accompanied by malaria. 
The results of our study of Anopheles rossii as a whole tend 
to confirm the conclusions of investigators in India that this 
species is responsible for little if any transmission of malaria. 
There is probably no locality in the Philippines where this species 
does not breed at some time during the year and in most places 
very plentifully. If it were a carrier, we would expect a cor- 
respondingly wide distribution of malaria, yet our survey shows 
that there are many localities where A. rossii breeds at almost 
all times of the year in large numbers and close to houses, yet 
these localities show an index of 0. This is true of towns like 
Manila, Paranaque, and Cebu city and other coast towns of 
Cebu where A. rossii breeds abundantly in salt or brackish 
water, and in towns like Calamba in Laguna Province and Orion 
in Bataan Province, surrounded by rice paddies, which afford 
fresh-water breeding places the year around. 
There also seems to be little correlation between the breeding 
places of A. barbirostris and A. sinensis and the presence of 
indigenous malaria. The occurrence of both in irrigated rice 
paddies where the malarial index has been found to be low 
indicates that they are not important carriers. Anopheles barbi- 
rostris and A. sinensis do not seem to be by preference house- 
seeking species. 
Anopheles maculatus probably transmits malaria in certain 
localities and at certain seasons in the Philippines. In Decem- 
ber, 1913, this species occurred in considerable numbers in a 
brook at Canlubang. On the banks of this brook a barrio is 
located in which considerable malaria occurred at that time and 
earlier in the season, and it is possible that A. maculatus was a 
carrier. At Camp Stotsenberg, Pampanga Province, this species 
