500 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
Dents sp. 
leaves 
20% 
negative 
stem 
20% 
positive 
flowers 
10% 
negative 
leaves (boiled) 
20% 
negative 
Derris polyantha (common name “Tugle,” “Malagogon-dapo”) is reported by Fox¬ 
worthy and Elmer in "The Flora of Makiing and its Vicinity” to contain a 
fish poison in its bark. 
Many species of Derris in the Philippines are rank-growing vines, 
found in such abundance on the mountain sides that they would prob¬ 
ably furnish a continuous supply of the raw material at a medium cost 
of harvesting. 
The following experiments in extraction and insecticidal tests were 
made with the ground root of Derris sp. diluted with calcium carbonate 
and with commercial liquid and dust preparations. Four extracts were 
prepared from dried roots of Derris sp. (probably elliptica) using as 
solvents, petroleum ether, ether, alcohol and water. The ether ex¬ 
tracts were of a yellowish brown structure, brittle at room temperature 
and soluble in some of the alcohols. The alcoholic extract was of a 
gummy nature and the water extract flaky. Pyridine was found to be 
the most satisfactory solvent for all the extracts except the alcoholic, 
which was soluble in both ethyl and methyl alcohol. From this it would 
seem that an alcoholic extract dissolved in wood alcohol would be an 
economical commercial preparation, or an ether extract dissolved in 
pyridine. Variations from these results might be found with different 
species of Derris. 
Tests of the susceptibility of the guinea-pig to Derris extracts were 
made by sub-cutaneous, abdominal injections with the following results: 
(a) One-fourth cc. of a solution made by dissolving .002 gm. pure 
petroleum-ether extract dissolved in one-half cc. of pyridine,—no 
pathological symptoms. 
(b) One-fourth cc. of .103 gm. ether extract dissolved in one-half 
cc. of pyridine,—symptoms: rapid irregular heart action, loss of appe¬ 
tite and weight for three days followed by a rapid return to normality. 
This indicates a very slight susceptibility to the action of Derris, 
since even the smaller amount was much in excess of that which would be 
absorbed by light dustings. 
The commercial extract of sixteen per cent concentration diluted 1 
to 500 gave a 13% control on Aphis nerii Fons., and a 50% control on 
the green peach aphid (Rhopalosiphum persicae Suker). Dilutions 
of 1 to 300 gave a maximum control of 68% on the latter species of 
aphid and 25% on the red spider (Tetranychus telarius Linn.). Dilu- 
