92 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



At the present time it is probably abundant in all the larger cities of 

 the United States except in the South, where it is replaced by another 

 species. 



The hlack, or house, rot. — The black rat, or house rat {Mus rattiis), 

 was in all probabilitj^ originall}^ a native of Asia. The time of its 

 introduction into Europe is uncertain, ])ut in the middle ages it was 

 the common house rat of central Europe. The date of its introduc- 

 tion into the New World is placed as early as 1544, or more than 

 two liundred years previous to that of the brown rat. It evidentlj^ 

 became very generally distributed along the coasts and in the principal 

 seaports, and by the middle of the present century was known as far 

 north as Halifax and Montreal, Canada, and on the Pacific coast at San 

 Diego and Humboldt Ba}^ California. Since the introduction of the 

 brown rat, the black rat has become comparatively rare in most places 

 where the former is abundant. In the Laccadive Islands, in the Indian 

 Ocean, the black rat seems to have modified its habits and become 

 arboreal. It is said to live in the crowns of the cocoanut trees with- 

 out descending to the ground, and to do great damage hy biting off 

 the nuts, upon which it feeds, before they are ripe. 



The roof, or n'hite -bellied, rat. — The roof rat, or white-bellied rat 

 {Mus alexandrinus), is a native of Egypt, Nubia, and northern 

 Afi'ica, and evidently found its way to America by waj^ of Italj' and 

 Spain at an earlj' date. It probably reached this continent long 

 before the brown rat, but the exact date of its arrival is uncertain. 

 It is common in Brazil, in some parts of Mexico, and in the southern 

 United States, and is known to occur at least as far north as the Dis- 

 mal Swamp, in southern Virginia. 



Tlie house mouse. — The well-known house mouse {3Ius musculus) 

 is i-eadilj' distinguished from the native white-bellied mice of North 

 America by its nearly uniform brownish color above and below. It 

 is a native of Europe and central Asia, l)ut now occurs all over the 

 world. In the United States it is found from Florida to Maine, and 

 from San Diego to the Pribilof Islands. It is not restricted to the 

 seaports, as it made its way inland at an early date. Sir John Rich- 

 ardson, in 1820, mentions having seen a dead mouse in the store- 

 house of the Hudson Bay Companj', at York Factory, among packages 

 of goods brought over from England, and states that the house- mouse 

 was introduced at Engineer Cantonment, on the Missouri River, near 

 Council Bluffs, Iowa, by Long's P^xpedition in 1810-20. J>y 1855 it was 

 found at many points in the interior, such as Prairie Mer Rouge, La. ; 

 Fort Riley, Kans. ; Fort Pierre, S. Dak.; Fort Redding, Cal., and 

 Parras, Coahuila, Mexico. It has even penetrated to such points as 

 the Iluachuca Mountains in Arizona, where it was introduced about 

 1801 in a wagonload of seed grain. It reached Bering Island, one 

 of the Commander group off Kamchatka, in 1870, in a cargo of flour 

 shii)i)ed from San Francisco in the schooner Justus. In the southern 



