if 



7 



United States Dopartment of the Interior 

 Pish and YJildlife Service 



ITildlife I^aflo't 264 



Chicago 54, 111, 



De comber 1944 



EISTIC AGENT IN TOXIC RAT BAIT, A SAFEGUARD 



.'■ FOR DOGS MP CATS 



By H. J. Spencer, Biologist, V/ildlife Research Laboratory 

 Division of 'Tildlife Research 



Red squill is an important raticide because of its general effective- 

 ness combined Kith emetic properties that serve as a .protection "against 

 fatal poisoning of domestic animals but do, not operate in the. same Vifay 

 ajnong rats. Its inadequacy in controlling rats under some conditions,. ; 

 however, necessitates the frequent use of other less specific poisons, 

 the high toxicity of which renders their- general employment inadvisable. 

 'Tith increased demand for such potent poisons in rodent control the need 

 for safeguarding their use is of prim© importance. 



EARLIER STUDI3S 



The staff of the Wildlife Research Laboratory, at Denver, Colo., 

 early in 1937 actively engaged in the study of so modifying drastic 

 poisoned baits that when used in controlling rats they would be harmless 

 to other animals. Various emetics, including co-pper sulphate, zincf 

 sulphate, and' tartar emetic, used in 1 to 5 percent concentrations in 

 hamburger bait, wore tested on dogs. Of these, copper sulphate gave 

 indication of being most useful*. In preliminary trials rats did not seem 

 to discriminate against a 2-percent concentration of this salt in thallium- 

 poi'-soned bait. 



Later copper sulphate was used in zinc phosphide baits in the control 

 of field mice (Microtus) in orchards in the New England States, Acceptance 

 was considerably lower than for bait free of the emetic but v,ras improved 



as the quantity of copper sulphate was decreased, A 4 to 1 ratio, however, 

 did not materially improve acceptance over that of the 3 to 1 mixture. 

 Dogs survived test feeding of mouse bait containing zinc phosphide -and copper 

 sulphate mixed in ratios of even 2 to' 1, and 1 to 1« 



I L I r ^fi /■ . R Y 



I GlrR-RF^ ? \'-\-\\ RECORD 

 ■ 1^ FEB ^ 7 1945 ^ 



U»S.-.K ,:; rvV 0- ASRIOULTUaE 



