25 



of him, all moving in one direction. The host stretched away as far 

 as they could be seen in the dim light. These animals invaded the 

 farms and villages of the surrounding country and caused heavy 

 losses during the winter and summer of 1904. A local newspaper 

 stated that between March 20 and April 20, 1904, Mr. F. W. Mont- 

 gomery, of Preemption, Mercer County, killed 3,435 rats on his farm. 

 He caught most of them in traps."* 



In 1877 a similar migration of rats into parts of Saline and 

 Lafayette counties, Mo., took place.* Also, one came under my 

 own observation in the Kansas River valley in 1904. This valley, for 

 the most part, was flooded by the great freshet of June, 1903, and 

 for about ten days was covered with several feet of water. Probably 

 most of the rats in the valley at the time perished in the flood. Yet 

 in the fall of 1903 much of the district was visited by hordes of rats, 

 which remained during the winter and had so increased by the follow- 

 ing spring that serious losses to grain and poultry resulted. 



No doubt most of the so-called migrations of rodents, were all the 

 facts known, could be accounted for as instances of abnormal repro- 

 duction or of failure of food supply in one place, compelling change of 

 habitat. In England a general movement of rats inland from the 

 coast occurs every October. This is known to be closely connected 

 with the closing of the herring season. During the fishing the 

 rodents swarm to the coast, attracted by the offal left in cleaning the 

 herring; and when this food fails, the animals troop back to the 

 farms and villages. 



In South America plagues of rats are often periodical, occurring 

 in Parana, Brazil, at intervals of about thirty years and in Chile at 

 intervals of from fifteen to twenty-five years. It has been dis- 

 covered that these plagues in the cultivated lands follow the ripen- 

 ing and decay of the dominant species of bamboo in each country. 

 The ripening of the seed furnishes for two or more years a favorite 

 food for rats in the forests, where the animals multiply greatly. 

 When this food fails, they are forced to the cultivated lands for 

 subsistence. In 1878 almost the whole crops of corn, rice, and man- 

 dioca in the State of Parana were destroyed by rats, causing a serious 

 famine."" 



An invasion of rats ( Mus rattus) in the Bermuda Islands occurred 

 about the year 1615. Within two years they had increased so 

 alarmingly that none of the islands was free from them. The 

 rodents "devoured everything that came in their way — fruits, plants, 

 and even trees" — so that for a year or two the people were nearly 

 destitute of food. A law was passed requiring every man in the 



oMoline (111.) Evening Mail, Apr. 25, 1904. 



6 Forest and Stream, vol. 8, p. 380, July 12, 1877. 



c Nature, vol. 20, p. 65, 1879. 



