18 



OBCHABD HICE AND VOLES 



Alan Eaton 



Department of Entomology 



University of New Hampshire 



Mice and voles are closely related rodents that can be distinguished from 

 each other on the basis of tail and ear size, among other minor differences. 

 In New England, mice are not a problem in orchards, but two species of voles 

 frequently cause serious damage. These pests are the meadow vole and the pine 

 vole. Meadow voles range throughout New England, but pine voles are known to 

 be present only from southern New England to southern Vermont, New Hampshire, 

 and the southern tip of Maine. 



Meadow voles inhabit the orchard floor, developing a network of surface 

 trails through the groundcover and feeding primarily on grasses and fleshy 

 herbs. This species usually does most of its damage during the winter when 

 herbage is less abundant, but damage is possible at any time of the year. They 

 chew away areas of bark and cambium that can be reached from the ground or from 

 higher positions in or on snow cover. In some soils they will burrow and 

 sometimes are responsible for trunk girdling several inches below the ground 

 surface. 



Pine voles travel either in surface trails or in burrows 3 or more feet 

 deep depending somewhat on soil conditions. In solid grass sods, they may be 

 almost totally subterranean; but where the groundcover contains a high 

 percentage of broadleaf herbs, pine vole may travel on the surface. During the 

 cold months, their activity is pretty much limited to the underground burrows. 

 When herbage is abundant, pine voles store caches in the tunnel system for 

 later use. They feed upon bark and cambium primarily below the soil line, and 

 chew off small roots up to about the diameter of a pencil. All commercial 

 apple cultivars and their seedlings, as well as the available rootstocks, are 

 very susceptible to vole feeding. 



Identification of Pest Species 



When vole damage is apparent, it is important to determine which species 

 is responsible. Some of the management practices used for meadow voles are not 

 effective against pine voles. Identification of the species may require 

 trapping. Use snap traps baited with rolled oats, or peanut butter, or a 50:50 

 mixture of these two. Fresh apple pieces are also a good bait. Place traps 

 across active runs, including those that lead into underground burrows if they 

 are present. Cover the trap with an apple box or a similar cover. This will 

 exclude birds and cats and help you locate the trap trees in the orchard. Set 

 enough traps to be sure of catching 5 to 10 voles from various locations in the 

 orchard. Check the traps after only one or two days. Tail length is useful 

 for identification. The pine vole tail is very short — about the same length as 

 the hind foot (not the leg!), measuring 3/^ inch or less. The meadow vole's 

 tail is about twice the length of its hind feet, reaching 1 1/2 to 1 3/^ inches 

 on adults. Both species have chunky bodies and small beady eyes, and their 

 ears are small and almost concealed in fur. The fur color is dark brown or 

 gray-brown. If you catch a long-tailed specimen, it is likely to be a white- 



