MOUSE PLAGUES, THEIR CONTROL AND PREVENTION. 305 



of March, 1008, aiul in more than usual abundance until May, and 

 in some few centers even later. But they did not noticeably breed 

 Avith the return of favorable weather, and by August had practically 

 disappeared. 



THE PLAGUE MOUSE. 



The mice whicli produce plagues almost invariably belong to the 

 genus Microtus^ a group represented in the United States by about 

 50 species. Variously known in European countries as voles, wiilil- 

 miiuse, and canipagnols, and in the United States as slxjrl -tailed field 

 mice or meadow mice, their general characteristics are everywhere 

 the same. Except in the deserts, one or more species are present in 

 practically all parts of the country, and normally they are among 

 the most abundant of mammals. The annual damage they cause to 

 crops, nurseries, and orchards in the United States has been esti- 

 mated at over $:3,00(),000. 



With few exceptions, the short-tailed field mice are readily dis- 

 tinguishable from other mice by their stout, chunky bodies, short 

 legs, short, round tails, blunt muzzles, short ears, and rather small 

 eyes. Most of them are dark brownish or grayish brown in color 

 and considerably larger and heavier than the common house mouse. 

 (PI. XXIII.) 



They live almost everywhere in damp meadows, where their pres- 

 ence may be detected among the grass and weeds by small, well- 

 defined, crooked trails, along which at intervals are little heaps of 

 fresh grass or other herbage. In alfalfa or clover fields their numer- 

 ous small burrows are usually in colonies. As a rule they appear 

 first along ditches or about damp areas, where dead plants are almost 

 certain evidence of their work. 



CONTROL or MOUSE PLAGUES. 



In the past many methods of destroying field mice have been tried, 

 yet the records describe no instance in which well-established plagues 

 have been successfully suppressed. Failing to recognize the early 

 stage of the plague, the people in stricken districts have usually not 

 adopted vigorous measures until after the fields were swarming with 

 mice. The failure, then, has been due partly to lack of cooperation 

 and partly to lack of knowledge of quick, cheap, and effective meas- 

 ures. Without witnessing such a plague one can hardly form a con- 

 ception of the almost incredible numbers of mice and of the magni- 

 tude of the task of destroying them. 



Among methods of little value which have been tried in other 

 countries to rid the land of these scourges are rolling the land with 



