15. 



CONTROLLING ORCHARD MICE 



Edward R. Ladd, Wildlife Biologist 

 U.S. Fish and Wildlife Service 



Unless preventive measures are taken, orchardists can expect 

 mouse damage to fruit trees during the winter months. Most fruit 

 growers know from past experience which areas or blocks of trees 

 are likely to be damaged. Still, it is a good idea to check the 

 orchard in the fall to determine the status of old problems, and 

 if any new trouble areas have developed. Areas having clean mouse 

 trails, chewed apples, or the characteristic fan-shaped mounds 

 of soil, pushed up by pine mice, are indicative of potential mouse 

 damage problems. The amount of these indicators found will deter- 

 mine if greater than normal mouse control is necessary. 



Meadow Mice 



These are the surface- living mice most common to orchards in 

 the Northeast. They injure fruit trees by chewing bark from the 

 root collar upward. Since these mice, like all animals, require 

 food and shelter for survival, some protection can be gained by 

 close mowing of the vegetation in the orchard. Control of grass 

 and weeds in the orchard should be done periodically throughout 

 the year, but especially in the fall. Close mowing removes cover 

 and makes the area less acceptable to mice. Any reduction in cover 

 should help prevent damage prior to snowfall. 



Control of vegetation should not be used as the primary mea- 

 dow mouse control method in the fall, but merely as a supplement 

 to the use of toxic baits. Remember that during the winter deep 

 snow will provide the needed cover for mice and they will be able 

 to reach the trees without exposing themselves. 



The best method for controlling orchard mice is still the proper 

 application of mouse control baits. All sections of the orchard hav- 

 ing meadow mice should be treated in the fall following apple har- 

 vest. Those areas having an overabundance of mice will need an ex- 

 tra treatment, if for some reason the initial one does not give 

 adequate control. If mouse concentration sites with wood, roofing 

 squares or other materials are used, they make excellent areas to 

 check on mouse activity in addition to their bait exposure use. 



In addition to regular mouse control within the orchard, the 

 mowing and baiting of buffer areas is still recommended. This is 

 particularly true if fall orchard checks show high mouse activity. 

 These treated buffer strips should help reduce mouse migration into 



