﻿164 The Philippiiie Journal of Science i9i4 



Since the establishment of the permanent settlements of the 

 San Jose Estate and the Mindoro Company at San Jose, the 

 outbreaks of malaria have been so frequent and of such a per- 

 nicious type, both among officials and laborers, that the companies 

 have found it very much to their advantage to take active steps 

 to eradicate mosquitoes within the inhabited area of their planta- 

 tions and to screen the houses of those employees intelligent 

 enough to keep screens in repair and screen doors properly closed. 



The area shown on the map, inclosed within solid red lines, 

 has been practically freed from both anophelines and culicines 

 by the process of drainage and oiling, but outside this area there 

 are breeding places of both Myzomyia rossii and Culex ludlowii, 

 the two forms being usually associated in the same breeding 

 places. (Plate I.) 



Busuanga River irrigation site. — This meandering river is an 

 ideal place for the best development of Myzomyia and Culex, it 

 being, at the time of my visit, somewhat low and its valley 

 thickly dotted with isolated pools in which algae grew most 

 luxuriantly and mosquito larvae bred abundantly. 



Enough larvae of Myzomyia were found in the intake site of 

 the company's irrigation ditch to keep the colony in a con- 

 tinuous state of malarial infection. Indeed, several Filipinos 

 and Americans who had been sleeping for a number of weeks 

 at this place were in hospital suffering from severe malaria at 

 the time of my visit. 



The same abundance of anopheline larvae was noted at the 

 Magbando Camp, some 3 kilometers southwest of San Jose, and 

 where the river had during 1912 carried away about 3 hectares 

 of sugar cane. 



Railroad. — The entire line of the railroad, from the wharf at 

 the port of Mangarin to the line limit for antimosquito measures 

 at San Jose, lies first through tidal swamp land and then through 

 land containing creeks, streams, and more or less stagnant ditches 

 and ponds where Myzomyia larvae were found Avithout exception 

 and in abundance. 



The ease with which mosquitoes can be carried from this 

 region to the town of San Jose will be more apparent when it 

 is stated that in a trip made after nightfall from Mangarin 

 wharf to San Jose, in one of the open passenger cars of the 

 company, I captured at least 3 females of Myzomyia rossii 

 attempting to bite me, who was one of at least 30 passengers. 

 It might also be said that in the whole trip of 15 kilometers 

 which consumed just seventy minutes, but two stops were made. 

 There was absolutely no breeze at this time. 



