10 THE BROWN EAT IN THE UNITED STATES. 



for care in the disposition of refuse and the protection of food mate- 

 rials. Tightly closed garbage cans frequently emptied will go far 

 toward limiting the food available for rats. Grain bins in private 

 and public stables, now affording food and harborage for thousands 

 of rats, and public markets and feed, provision, and grocery stores, 

 notoriously lacking in protection against rats, should have their con- 

 tents safeguarded from these animals. 



(2) The rat-proof construction of dwellings and public buildings. — 

 The advantages of cement in the cellars and foundations of public 

 and private buildings are now so well understood that the rat-proofing 

 of buildings by cement construction and other necessary measures 

 should be no longer left to individual inclination and judgment, but 

 should be incorporated in building regulations, and these strictly 

 enforced. The additional expense, compared with the advantages, 

 is trivial. 



The above measures are of first importance, but they will not 

 entirely solve the problem of rat repression. The destruction of 

 rats, wherever they are numerous, is very important and at times 

 absolutely necessary in the interests of public health. Hence in the 

 following pages are given the best methods known for destroying 

 rats, many of which have been developed b}^ experiments and 

 practical trials. Such methods, however, are fallible and at best 

 inferior to preventive measures. The cutting off of the chief sources 

 of food supply will limit the increase of the pests to a minimum, 

 while the general construction of rat-proof buildings will deprive 

 them of shelter and breeding places. The two measures will thus 

 strike at the very root of the evil, ~nd if supplemented when necessary 

 by a vigorous campaign of destruction will prove vastly more 

 effective, much less expensive, and productive of far more enduring 

 results than any measures hitherto attempted. 



DESTRUCTIVENESS OF THE BROWN RAT. 



At the head of the rat family for destructiveness stands the brown 

 rat (Mus norvegicus), called also gray rat, house rat, barn rat, wharf 

 rat, and Norway rat. (PI. I, fig. 1.) Like all members of the genus 

 Mus found in America, the animal is not a native, but is an immi- 

 grant from the Old World. In spite of constant warfare waged against 

 it, the brown rat has steadily increased in numbers, and has spread to 

 almost all parts of the country reached by railways or by steamship 

 lines. Accidentally brought to our shores after the middle of the 

 eighteenth century, in most places it has driven out or exterminated 

 its less robust relative, the black rat. The dominance of the brown 

 rat is probably due to its superior strength and ferocitVj its greater 

 fecundity, its peculiar adaptability to various environments, and its 

 more pronounced burrowing habit. 



