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 know 

 from past experience which areas and blocks of trees are likely 

 to be damaged. Still, it is a good idea to make a survey of the 

 orchard in the fall to determine whether 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 potential mouse damage problems. These are the areas 

 where a thorough mouse control program should be undertaken. 



MEADOW MICE 



These are the surface- li vi ng mice most common to orchards in 

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

 root collar upward. Since these mice require food and shelter 

 for survival, some protection can be gained by eliminating these 

 two requirements. Control of grass and weeds in the orchard 

 should be done periodically throughout the year, but especially 

 in the fall. Close mowing and removing hay destroys cover and 

 meadow mice are less active in these exposed areas. This 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 use 

 of zinc phosphide-treated grai ns--ei ther oats or corn. These 

 treated grains may be applied either with the trail builder machine 

 or by broadcasting at a rate of 6-10 pounds per acre. All sections 

 of the orchard having meadow mice should be treated in the fall. 

 Those areas having an overabundance of mice will need an extra 

 treatment, if the initial one does not give adequate control. 

 Hand placement or a broadcast of Zinc Phosphide Rodenti ci de-treated 

 apple cubes is a good follow-up method. 



Periodic checks during the winter months, particularly after 

 a thaw, may reveal spots still having meadow mouse infestations. 

 A tablespoon of zinc phosphi de- treated grain poured into the holes, 

 may give added protection for the remaining winter months. 



PINE MICE 



Pine mice are an underground species found in many orchards in 

 the Northeast. These mice damage trees by girdling the root sys- 



