fe Pe ie aN Ode Pe 
a) USDEPARTENT OAGRCLIT 
No. 165 
o 
= 
Daas 
2 
ae) 
aes 
or 
Z= 
c) Q 
YD 
Contribution from the Bureau of Entomology, L. O, Howard, Chief. 
December 31, 1914. 
(PROFESSIONAL PAPER.) 
QUASSIIN AS A CONTACT INSECTICIDE. 
By Witt1am B. PARKER, 
Entomological Assistant, Bureau of Entomology.’ 
INTRODUCTION. 
Quassia chips, the active principle of which is quassiin, have been 
employed for many years in the preparation of spray solutions for the 
control of the hop aphis (Phorodon humuli Schr.). Several formulas 
have been followed, and there are several methods of preparation 
according to these formulas. Several factors have brought about the 
variations in the formulas, (1) instability in the percentage of quassiin 
in the chips, (2) the total amount of available quassiin in the chips 
probably not extracted, due to the method of preparation, and (3) 
the fact that there appeared to be no fundamental data accumulated 
on this subject. The writer accordingly commenced the investiga- 
tion, which has been taken up from an insecticidal standpoint, and 
any chemistry that is mentioned other than very simple matters is 
taken from the various sources. Acknowledgments are due to Prof. 
George P. Grey, of Berkeley, Cal., and Mr. G. H. P. Leichthardt, of 
Sacramento, Cal., for valuable suggestions, and to Mr. R. E. Camp- 
bell, of the Bureau of Entomology, who ably assisted the writer in 
determining the efficiency of the several formulas. 
During the investigation of the life history and control of the hop 
aphis ? it was observed that there were several formulas for the use 
of quassia chips. These all appeared to give satisfactory results 
when carefully prepared and applied, but it will be observed from 
the following formulas that if the weaker one killed the aphides, the 
use of the stronger one resulted in a waste of material and extra 
expense. 
1 Resigned August 31, 1914. 
2 Parker, Wm. B., The Hop Aphis in the Pacific Region. U.S. Dept. Agr., Bur. Ent. Bul. 111, 39 p., 
8 fig., 10 pl., May 6, 1913. 
Note.—The results of an investigation to determine the most suitable solution of quassiin for use as aspray 
for the control of the hop aphis are discussed in this bulletin. 
67215°—14 
