54 RODENTS OP IOWA 



beings. During the summer months serious losses to grain in the 

 shock and stack are sustained by their depredations. 



When present in any numbers this mouse destroys considerable 

 amounts of food and stores, yet all efforts to exterminate it in the 

 United States have proved futile. Indeed its numbers seem in no 

 way to be diminished. 



Various control measures have been employed in keeping down 

 the numbers of house mice, such methods being 1 applicable, in gen- 

 eral, for the house rat. The details of these measures are discussed 

 in connection with the latter animal. Suffice it to say here that 

 precautionary and concerted action will do more toward* the lessen- 

 ing of damage than is generally believed and such measures should 

 receive widespread support. 



HOUSE RAT. BROWN RAT. NORWAY RAT. 



Rattus norvegicus (Erxleben). 

 [Mus] wyrvegicus Erxleben, Syst. Regni Anim., I, 381, 1777. 



Description. General color above grayish brown, darkest on 

 middle of back, the over hairs of the upper parts tipped with black ; 

 sides grayer; color below pale grayish brown; hair coarse; tail not 

 longer than head and body, usually less; tail scaly and sparsely 

 haired, above dusky, beneath paler. 



FIG. 12. The Brown Rat. (From U. S'. Department of Agriculture, Bureau of 



Biological Survey.) 



Measurements. Total length, 16.50 inches; tail vertebrae, 7.10 

 inches; hind foot, 1.75 inches. 



