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FOOD AND SHELTER are as essential to rats as to other animals, and the
removal of these offers a practical means of permanent rat control.
The number of rats on premises and the extent of their destructiveness
are usually in direct proportion to the available food supply and to
the shelter afforded. Rat proofing in the broadest sense embraces not
only the exclusion of rats from buildings of all types but also the
elimination of their hiding and nesting places and cutting off their
food supply. Through open doors and in other ways, rats may frequently
gain access to structures that are otherwise rat proof, but they can
not persist there unless they find safe retreats and food. When rat
proofing becomes the regular practice the rat problem will have been
largely solved.