Technical Bulletin No. 134 
November, 1929 
UNITED STATES DEPARTMENT OF AGRICULTURE 
WASHINGTON, D. C. 
RED-SQUILL POWDERS AS RATICIDES 
By J. C. Munch/ Consulting Pharmacologist, James Silver, Associate Biologist, 
and E. E. Horn, Associate Biologist, Division of Predatory-Animal and Rodent 
Control, Bureau of Biological Survey 
CONTENTS 
Page 
Purpose of investigation 1 
Source and structure of squill 2 
Results of previous investigations 2 
Chemical 2 
Physiological 3 
Toxicity 3 
Use of squill as rat poison 4 
Experimental procedure 5 
Preparation of powder 5 
Method of feeding. 9 
Effects of squill on rats 10 
Results of investigation 10 
Effect of temperature on toxicity 19 
Direct oven drying versus preliminary air 
drying 19 
Effect of fermentation on toxicity and 
yield of powder 20 
Effect of variability of squill bulbs on 
toxicity 20 
Effect of intensity of color of squill bulbs 
on toxicity 21 
Page 
Results of investigation— Continued. 
Toxicity of white squill to rats 22 
Toxicity of calcium oxalate to rats 22 
Preparation of red-squill powder on a 
semicommercial basis 22 
Relative susceptibility of white rats and 
of wild (brown) rats to squill powders. 24 
Effect of red-squill powders on domestic 
and other animals 25 
Yields of toxic squill powders ("rat 
units") 27 
Stability of squill powders 31 
Acceptance tests 31 
Commercial squill rat poisons 31 
Extraction of toxic principles by various 
solvents 32 
Suggested method of preparation of toxic 
squill powders 33 
Conclusions 34 
Literature cited 35 
PURPOSE OF INVESTIGATION 
The principal requirements for an ideal rat poison are safety, 
effectiveness, and economy. The rat poisons in most general use 
to-day (arsenic, barium carbonate, phosphorus, and strychnine) have 
toxic properties that seriously menace the safety not only of ^vild 
and domestic animals, but also of human beings. Red squill is rela- 
tively safer and more nearly approaches the ideal rat poison. Animals 
other than rats usually refuse to eat red squill in the concentrations 
used for rat baits. The difficulty of obtaining a uniformly toxic 
preparation of red squill has retarded its development for this pur- 
pose. To contribute to the information needed for the production 
of a potent red-squill preparation for the efficient destruction of rats, 
the investigation here reported was undertaken. 
Acknowledgment: The work here reported was a cooperative study by members of the Bureaus of Chem- 
istry, Biological Survey, and Plant Industry. The writers wish to express their thanks to the following for 
assistance in various wavs during the four years of the investigation: Bureau of Chemistry— N. O. Bar- 
bella, R. M. Hann, D. B. Jones, G. L. Keenan, B. A. Linden, E. W. Schwartze, K. A. Smith, and C. Q. 
Spencer; Bureau of Biological Survey— C. C. Carr, F. N. Jarvis, and M. A. Stewart; Bureau of Plant In- 
dustry— O. F. Black, J. W. Kelley, A. F. Sievers, and W. W. Stockberger. 
1 Formerly pharmacologist of the Bureau of Chemistry. 
53580°— 29 1 I 
