-22- 
Letvae deed efter — 
Materiel 
Dilution 
1 /.our 
24 hours 
Number 
.~ber 
Crude ter>hrosin 
1:100,000 
1:250,000 
1:500,000 
Alcoholic extract of 1:300 
Tephrosia vogelii seedsl:500 
1:750 
Alcoholic extract of 1:100 
Tephrosia vogelii 1:250 
leaves 1 : 500 
Water extract of 1:100 
Teuhrosie vogel'ij- 1:250 
leaves 
■ 8 
10 
1 
4 


8 
10 
2 
4 

1 
9 
10 
4 
5 


4 
10 

5 
Theobaldia annuleta (Schrank) 
According to G-imlette (ill), writing in 1923, H. E. Durham 
found in England in 1902 that larvae '"ere killed in a 1:40,000 sus- 
pension of the dried Doddered crude root of Derris elliptica . A 
solution of 1:10,000 killed the larvae in 29 hours and the pupae in 
from 24 hours to 3 or 4 days. 
Culicidae (unidentified spn.) 
Daniels (65_) in 1905 ^rote th?t e fragment of crushed fresh 
derris root cen be used effectively under all circumstances under 
which kerosene can be used to destrov mosouito larvae. 
Tattersfield and Roach ( 271 ) in 1923 reported work on derris 
done by Durham between 1902 and 1907. He found mosouito larvae and 
puoae to be usefully susceptible test insects. 
De Ong and White (71) in 1924 reported that a commercial der- 
ris extract of 16-percent concentration diluted 1:500, added to 
mosquito-infested water, killed 65 percent of the larvae but had 
no effect on the pupae. The pondered derris root (undiluted) 
sprinkled on the surface of the ^ater killed 90 percent of the 
larvae in 2 to 4 hours. 
Castillo (59) in 1926 reported the results of studies on the 
insecticidal -properties of three species of - Derris gro-in^ in the 
Philippines, namely, D. nolyenthe Perk. , D. v> ulir-ninensis Merr., 
and D. ellvptica Benth. The roots -ere cut into thin trensverse 
slices and dried in an oven at 40° C. until the "eight remained 
ffirly constant. The dried material pps then comminuted in a 
mortar and the po^derin^; finally conrleted in a meet grinder. The 
fine powder ^as separated from the fibers by sifting through fine- 
meshed cloth. On mosouito larvae the most effective concentrations 
