CULTIVATION TO DESTROY MICE. 55 



Trapping has special advantages for small areas such as lawns, 

 gardens, and vegetable or nursery pits and packing houses, where 

 a limited number of mice are present, and wherever, for any reason, 

 there are objections to the laying out of poison. As voles do not 

 readily enter cage traps, simple wnre traps of the guillotine order, 

 in which mice are instantly killed, are the most effective (text 

 figures 2 and 3). 



Traps without bait may be set across the runs of the mice, wdiere 

 the animals spring them by coming in contact with the trigger, 

 or they may be baited Avith oat or corn meal. For trapping pine 

 mice an opening should be made in the underground tunnel large 

 enough to receive the trap, which should be set across the bottom of 

 the runway. The traps may be baited or not, but the opening should 

 be covered. 



CULTIVATION. 



Thorough cultivation of fields tends to keep down the number of 

 voles. Cultivation implies the destruction of weeds and all the an- 

 nual growths that provide winter shelter for the animals. The mere 

 plowing of a field badly infested by mice is sufficient to drive out most 

 of them. However, as a rule the animals escape to adjoining fields 

 and return to their old haunts when growing crops or weeds afford 

 sufficient shelter. 



. The Scottish vole plague of 1892-93 originated in hill pastures, 

 where heather, moss, and numerous grasses afforded abundant shelter. 

 The outbreak on the border farms in 1876-77 occurred under similar 

 conditions. The Thessalian vole plague of 1891 and 1892 apparently 

 grew^ out of peculiar conditions of cultivation. The district visited 

 by the mice is an extremely fertile one on the plains near Larissa. 

 The lands are mostly in large holdings, the owners of which rent the 

 fields to peasants who live in the villages. Owing to primitive methods 

 of cultivation, each peasant has only a small tract. As the number 

 of renters is small, a system of rotation is practiced which brings the 

 same tracts into cultivation about once in three years, while two-thirds 

 of the district lies fallow. In the fallow lands voles multiply until at 

 times they invade the cultivated lands and ruin the crops." 



"WTiile a high state of tillage does not always bring immunity from 

 voles, it does nuich to lessen the danger of attacks from them. A sys- 

 tem which regularly brings all the land of a district under the plow 

 and permits little of it to lie unused will secure the greatest immunity 



from these pests. 



a Prof. T. Loeffler, Centralblatt fur Bakteriologie und rurusltenkunde, vol. 12, 

 pp. 1-17, July 5, 1802, 



