712 



Eesearch (Eat) Laboratory. 



[Nov., 



THE MINISTRY'S RESEARCH (RAT) 

 LABORATORY. 



C. L. Claremont, B.Sc. fLond.), F.I.C, 



Research Chemist^ Rat Destruction Brarich. 



At nrst sight it might he supposed that vat destruction is a 

 simple matter, not offering much scope for scientific research. 

 Such, however, is not the case, for although rat destruction has 

 been carried out for many years by empirical methods, no con- 

 siderable success has been achieved. Of late years, iioAever, 

 scientists and health officials all over the world have given atten- 

 tion to the subject, and there are gradually being accumulated 

 facts which, it is hoped, will lead to greater success in the future. 



The necessity for rat destruction cannot be questioned. 

 Statistics show the enormous material damage, amounting to 

 many millions of pounds sterling annually, caused by rats and 

 mice in destroying property, especially stored and gi'owing food- 

 stuffs; while the danger of rats and mice as carriers of diseases 

 which attack human beings and domestic animals is well known. 



Methods of Destruction. — Four methods of rat destruction 

 are available, namely, hunting, trapping, the use of a virus, and 

 poisoning. The rat population is largely limited in numbers by 

 the available food supply and shelter. Adequate rat proofing is 

 therefore desirable vdierever practicable : this alone will tend 

 to reduce their numbers considerably. 



The first two methods need not be discussed at length; both 

 c^^re Hmited in their application, and in the case of trapping there 

 is difficulty in taking sufficient numbers to clear badly infested 

 areas. Further, rats soon become wary of traps of all kinds and 

 avoid them. Mention might here be made of the method of 

 destruction known as the " Rodier " system. This depends on 

 trapping alive, destroying all females caught, and releasing the 

 miles. It is supposed that the males, then greatly outnumbering 

 the females, will prey on each other and on the surviving 

 females. 



The virus method, when introduced some years ago. was hailed 

 as a great advance in scientific rat destruction, but experience 

 has hardlv justified the claims made for it. It may be well to 

 explain the method. Some years ago, a French scientist found 

 that the mice in a certain area were dying in unusual numbers, 

 and on investigation the cause was traced to an intestinal germ. 



