Pine mice occur over the greater part of eastern United States from
the Hudson River Valley to eastern Kansas and Nebraska and from the
Great Lakes to the Gulf of Mexico. Inhabitants chiefly of forested
regions, they are unknown on the open plains. Ordinarily they live in
the woods, but are partial also to old pastures or lands not frequently
cultivated. From woods, hedges, and fence rows they spread into
gardens, lawns, and cultivated fields through their own underground
tunnels or those of the garden mole. The tunnels made by pine mice
can be distinguished from those made by moles only by their smaller
diameter and the frequent holes that open to the surface.
While the mole feeds almost wholly upon insects and earthworms, and
seldom eats vegetable substances, pine mice are true rodents and live
upon seeds, roots, and leaves. Their harmful activities include the
destruction of potatoes, sweet potatoes, ginseng roots, bulbs in lawns,
shrubbery, and trees. They destroy many fruit trees in upland orchards
and nurseries (fig. 3). The mischief they do is not usually discovered
until later, when harvest reveals the rifled potato hills or when
leaves of plants or trees suddenly wither. In many instances the injury
is wrongly attributed to moles whose tunnels invade the place or extend
from hill to hill of potatoes. The mole is seeking earthworms or white
grubs that feed upon the tubers, but mice that follow in the runs eat
the potatoes themselves.
[Illustration: FIG. 3.--Root and trunk of apple tree from Laurel, Md.,
gnawed by pine mice.]
Pine mice feed to some extent outside their burrows, reaching the
surface through the small openings made at frequent intervals in the
roofs of the tunnels. In their forays they rarely go more than a few
feet from these holes. Most of their food is carried under ground,
where much is stored for future consumption. While they differ little
from meadow mice in general food habits, their surroundings afford them
a larger proportion of mast. They are less prolific than meadow mice,
but this is more than made up for in the fact that in their underground
life they are less exposed to their enemies among birds and mammals.
Like meadow mice, they sometimes become abnormally abundant.
In the eastern part of the United States pine mice do more damage to
orchards than do meadow mice, partly because their work is undiscovered
until trees begin to die. The runs of meadow mice under grass or leaves
are easily found and the injury they do to trees is always visible.
On the other hand, depredations by pine mice can be found only after
digging about the tree and exposing the trunk below the surface.
The roots of small trees are often entirely eaten off by pine mice,
and pine trees as well as deciduous forest trees, when young, are
frequently killed by these animals (fig. 4).
[Illustration: FIG. 4.--Pine tree killed by pine mice.]