Cold blooded creatures such as insects and spider mites tend to come to mind when discussing pests of the landscape or garden. However, there are plenty of mammals that cause problems to our plants. A few animals get blamed for damage that they do not cause.

According to Rollin M. Baker's book, Michigan Mammals, most of the common mammal pests belong to the Order Rodentia. Common rodents include squirrels, chipmunks, mice, voles and woodchucks. They eat primarily plant matter. Insectivores are mammals that eat insects and include shrews and moles. Rabbits fall in the Order Lagomorpha which separates them from the rodents. The striped skunk is a relative of the weasel.

The squirrel group includes several related critters. Fox squirrels are the most common and are larger than their cousins the red squirrels. In the garden, red squirrels are the ones that chew the bark off trees such as sugar maples in order to feed on the sap. Fox squirrels bury their food in the ground while red squirrels hide theirs in a cache somewhere. If their supplies are stashed in the attic of a house and their entrance hole is blocked off, red squirrels will cause considerable damage forcing their way back in to get to their food.

The chipmunk and ground squirrels are also part of this group. They are both primarily ground dwellers and will dig holes and tunnels in the soil beneath and walkways. Chipmunks are small and have 3 dark stripes on their backs. The thirteen lined ground squirrel is larger and has 13 alternating light and dark stripes on its body.

Shrews are the world's smallest mammals. They are often mistaken for young mice but are actually easy to distinguish. Shrews have short, dense fur, long pointed noses and sharp, pointed teeth that differ from the chisel-like teeth of mice. Also, the opening for the shrews' ears is often concealed by the fur.

Ounce for ounce, shrews may be the most fearless, aggressive animals on earth. They will attack snakes, birds and mice many times their size. It is believed that they also feed on baby moles which may help keep these pests in control. Overall, these are very beneficial creatures and should not be needlessly destroyed.

Moles are another insectivore that cause homeowners, golf courses and others a lot of concern. The Eastern mole and the star nosed mole are the two species commonly found in this area. The Eastern mole leaves a trail of tunnels which may be clearly seen from the surface. The starnose mole tunnels deeper in the ground and leaves small mounds of soil at the surface to indicate their activity. These mounds are excess soil that they bring to the surface and are not entrance holes.

Moles are much larger than shrews and the distinguishing characteristics include their stout, cylindrical body covered with short, velvety fur, pointed, hairless nose, flesh colored tail and huge, spade-like forefeet which turn away from their bodies. Since they spend almost all their life below ground, their eyes are poorly developed and ears are not readily apparent. The starnosed mole has 22 fleshy, finger-like projections coming from its nose.

Many people think that moles eat only white grubs. In truth, they eat all types of insects and about half of their diet consists of earth worms. They eat very little, if any, vegetative matter and cause most damage by exposing the roots of plants to the air as they tunnel below.

The meadow vole falls into the same family as mice and rats but its rounded body, partly concealed ears, absence of a conspicuous neck and short tail distinguish it from the others. This is the creature primarily responsible for tunnels formed in the grass above ground. Once they are built, other critters such as field mice and house mice will move in and use the tunnels too.

Meadow voles and field mice are often responsible for damage to fruit trees by chewing at the bark during the winter. This usually occurs under the cover of snow and when weeds or grass are allowed to grow tall around the base of trees. Both critters love this type of habitat.

The largest of these pests is the woodchuck. The average adult's body is about 18 inches long followed by a tail 4 to 5 inches in length. They weigh between 5 and 12 pounds and, although they generally feed on the ground, they are good climbers and may be seen in trees or on split rail fences sunning themselves.

Woodchucks live in dens in the ground which may have as many as 5 different openings. One or more of the openings will be in the open and appear to be well-used but there will be others that are hidden nearby for fast retreats.

Unlike the Eastern chipmunk which stores nuts and seeds for winter feeding, the woodchuck relies solely on body fat to survive the winter. They nod off into hibernation in late fall and awaken again in the spring.

Reproduction occurs in mid to late April with the average litter being 3 to 5 young. If woodchucks become pests, it is better to control them prior to the addition of the young who will eventually want to establish burrows of their own in the area.

The woodchuck may be the largest pest in this group but the striped skunk is undoubtedly the smelliest! They can also be one of the most destructive when they make a midnight raid on the backyard in search of grubs. The result looks as if a group of extremely bad golfers had practiced all night without replacing a single divot. Fortunately, if the turf is laid back down in contact with the soil, most of it will grow back. 


Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.


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