DERRHS AS Ay PARASIEICIDE* 
By Paut M. GILMER 
Derris, as at present produced commercially, is the product ob- 
tained by grinding the dried roots of certain tropical plants belonging 
to the genus Deguelia. It has long been known that in the tropics 
the macerated roots of these plants are used by the natives for stupify- 
ing fish, a fact which has recently led to investigations as to its possible 
value as an insecticide. . 
In 1919, McIndoo, Sievers, and Abbot called the attention of ento- 
mologists to the insecticidal properties of derris. Independently, work 
was also done by E. Mathieu, 1920, in the Straits Settlements, and: by 
C. J. J. Van Hall, 1920, in the Netherlands’ East Indies, upon its 
___ properties as a controller of certain insect pests. All found it to possess 
marked insecticidal properties. 
In view of the desirability of developing satisfactory powders for 
the control of external parasites on animals, and because of the paucity 
of data concerning the properties of derris, it seemed desirable to 
extend these experiments with the following questions especially in 
mind : 
1. Is derris a practical and economical insecticide ? 
2. Is it advantageous to mix the powder with tobacco dust, and 
if so in what proportions is it most effective? 
3. What, if any, is the effect upon experimental animals? 
4. What is the most practical method of applying it ? 
5. Against what type of insects is it most effective? 
6. Are the powder and liquid extract equally effective and desirable? 
The actual material used in the following experiments is made 
from a South American species of Deguelia by an English corporation, 
It is prepared both as a powder and as a liquid extract. The powder 
is produced by grinding the dried roots, while the liquid derris is 
the result of the extraction by certain liquid solvents of the fibrous 
residue from the ground roots used in the production of the powder. 
It was furnished by the American Tobacco By-Products and Chemical 
Corporation, of Louisville, Ky., which at present holds a monopoly of 
the supply of the manufactured material for this country. 
The active principle is a resinous material, with a rather high 
toxic property so far as the higher invertebrates are concerned. It 
* Published with the approval of the Director as Paper No. 396 of the Journal Series 
of the Minnesota Agricultural Experiment Station. 
