moval of these breeding spots not 

 only deprives any remaining rats 

 of a place to live, but renders the 

 place unattractive to any new rats 

 that may stray in. 



RATPROOFING 



Once the bulk of the rat popula- 

 tion has been destroyed and the 

 harbors eliminated, it becomes 

 necessary to make the buildings 

 as ratproof as possible in order to 

 prevent reinfestation (fig. 12). 

 Cement, hardware cloth of 14-inch 

 or i/^-inch mesh, and sheet metal 

 of 26 gage or heavier are all good 

 ratproofing materials. The exte- 



rior of the building should be 

 carefully examined. All openings 

 larger than 1/0 inch must be closed 

 if rats are to be kept out. Wooden 

 sills and doors at ground level 

 should be sheathed in sheet metal 

 to prevent their being gnawed 

 (fig. 13). 



Windows less thaji 4 feet off the 

 ground in places where brown rats 

 are present, and at any height 

 from the ground where the climb- 

 ing rats are prevalent, must be 

 screened with hardware cloth. 

 Foundation walls, particularly 

 where utility lines enter the build- 

 ing, should be checked for open- 

 ings and pointed up with cement. 



13. — tdgcs of doors or other openings 



+h metal 



sheaihing. 



15 



