
X, B, 8 Barber et al.: Malaria in the Philippines Di 
TABLE X.—Haperiments with mosquito larvicides. 

















Ap- Preliminary survey. 
Ex- : proxi- 
ment Date. Locality. Nature of breeding place. width Coe aoa es 
; | stream No. BRB ; 
5 dips. 
1914 Meters. 
1| Apr. 14} Canlubang, Laguna_| Rocky brook with much |0.5-5 14 14 128 
vegetation and jungle. 
2| Apr. 15 | Santa Rosa, Laguna_| Swift clear brook; com- |2 -6 11 11 113 
paratively little vegeta- 
tion. 
3 | May 16 | San Jose, Mindoro__| Small brook; moderate |0.5-3 10 10 65 
amount of vegetation. 
4| July 31) Magdalena, Laguna_| Narrow ditch; much NSS eee es 26 113 
| grass. Water cut off 
| half an hour before oil- 
ing. 
Inter- 
ce ee eee ae 
; mate | proxi | spray Baas 
Hee mate jing and and after. 
tance | time. | reéx- 
Kind. Amount. |worked. erune Dips. | Larvze.| Before.| After. 
Liters. | Meters.|h. m.| Hrs. | 
Crude petroleum_) ) 1,000} 3 0O 20 | 200+ | 7 9.1} 0.035 |} 100:0.4— 
Larvicide, Dar- 0 || 400 30 | 24) 137 38 10.0 | 0.280 | 100:2.8 
ling. | 
Crude oil________- 8) 60 ss) Rye 8 6.5 | (ce) |a100:1 
| | 5| 81 1} 483) 0.012 | 100:0.3 
Kerosene _______- 4.5 | 370 20 | 16 55 0 4.3 0. 00 100:0. 0 
| (b) | many 0} 4.8] 0.00 | 100:0.0 








8 The depth of Nos. 3 and 4 was only from 3 to 5 centimeters except where very narrow. 
No. 1 averaged from 10 to 20 centimeters where the water was swift, and No. 2 had two or 
three times the flow of No. 1. In Nos. 1, 2, and 3 brooms were used to work the larvicide 
into the bank. In No. 4 kerosene was put on the water and simply splashed on the sides of 
the narrow ditch. Nos. 1 and 4, larvicide applied by one person. Nos. 2 and 3, larvicide 
applied by two persons, each taking one side of the bank. 
b19 days. 
¢ After treatment larve found only two or three times along the whole distance and in 
very small numbers. Exact data not recorded. 
a Hstimated. 
Preliminary experiments showed that the larvicide when 
merely poured on a stream and allowed to float down was in- 
effective, especially where the current was swift. So the lar- 
vicide was distributed along the margins and worked in 
mechanically. We found one of the best methods of distributing 
the oil was by means of a can provided with a long spout, and 
for working it into the breeding places we used, in most ex- 
periments, Filipino brooms made of stiff twigs. This method 
