34 



Rats and Mice 



the poison in loose materials (like meal) which cannot be carried 

 away, and also to prevent other animals from gaining access to 

 the poisoned food. Eats commonly become thirsty after poisoning, 

 and make their way to water ; it is, therefore, very necessary to 

 safeguard wells, etc., before commencing poisoning operations, 

 otherwise bodies of rats fall in, and their decomposition may have 

 serious consequences for the consumers of the water. 



Outdoor rats can be poisoned in their burrows by means of 

 gases — such as carbon bisulphide, sulphur dioxide, or chlorine. 

 Carbon bisulphide is the most convenient one to use out of doors, 

 but being very inflammable it requires great care in handling. A 

 piece of tow, cotton-wool or other absorbent material is saturated 

 with the liquid and pushed into the burrow as far as possible ; the 

 mouth of the burrow is then tightly closed with earth. Although 

 fumigation (preferably with sulphur dioxide) is most useful on 

 ships, it is not so effective in buildings owing to the difficulty of 

 confining the gas used ; and if effective indoors, the decomposition 

 of the dead rats in their inaccessible hiding-places is apt to entail 

 unpleasant consequences. After poisoning or fumigation the 

 burrows should always be run with gas-tar. 



In low-lying districts burrows may sometimes be flooded with 

 good effect ; many full-grown rats perish by drowning, and, what 

 is more important, many litters of young can be thus destroyed. 



Virus of one sort or another is occasionally effective. Such 

 bacteriological preparations are, however, costly, and they require 

 considerable skill in their use. Their virulence varies, and dis- 

 appears more or less rapidly on exposure to light and air. The 

 disease communicated usually propagates itself from rat to rat 

 very slowly ; and, what is worse, less than fatal doses render rats 

 immune. The harmlessness claimed for all towards animals other 

 than rats and mice is, at least in many cases, open to question. 

 Although bacteriology may furnish us any day with an efficient 

 means of destroying rats at will, it cannot be said to have done so 

 yet. Not one of the many preparations sold can be recommended 

 as a safe and thoroughly reliable means of destruction. 



Trapping" should be done at all times continuously and system- 

 atically, and special attention should always be paid to water- 

 courses and drains. Steel spring traps are the best for general 

 use, and when used out of doors they should be set early in the 

 day ; they should be regularly visited at dusk, late at night, and 

 early in the morning. Various baits may be used. The trap 



