Three squirrel species are commonly identified as living in Missouri and surrounding areas: the fox squirrel, Sciurus niger, the gray squirrel, Sciurus carolinensis, and the southern flying squirrel, Glaucomys volans. The red squirrel, Tamiasciurus hudsonicus, is present in the Midwest, but its native range does not include Missouri. Flying squirrels are seldom seen as they are primarily nocturnal animals. The gray squirrel is the animal most commonly seen in urban and suburban settings; in fact, the gray squirrel is the only tree squirrel many people ever observe in a natural setting. Squirrels usually live in wooded areas, often in close contact with humans. They ordinarily have two nests—one in a tree cavity and another in a fork of a tree. Young may be born and reared in either nest, but the cavity appears to be preferred, and nests in tree forks must be thought of as relatively temporary. Squirrels typically raise two litters of young each year, one in early spring and one in summer. Squirrels eat a wide variety of foods, which often brings them into conflict with gardeners. Their preferred foods in fall and winter are fruits and nuts. Hickory nuts are perhaps their favorite food, but they also depend heavily on acorns and osage orange fruits. Such foods often are stored for later use—in tree cavities or buried shallowly in the ground. In fact, squirrels probably are important members of the natural community in that they help propagate acorn- or nut-bearing trees by "forgetting" where they bury things. They prefer buds and twig tips in late winter and early spring. In summer, they eat fruits, berries, corn, mushrooms, and many other succulent plant materials. It is in this season that their depredations are most damaging and irksome to gardeners. Of less frequency, home invasion—into attics or other spaces in buildings—can be a problem. Finally, they are notorious raiders of bird feeders, where they are constant visitors, and where they often intimidate visiting birds.

Symptoms and Diagnosis

Observation usually is the only certain way to identify damage by squirrels. Missing or partiallyeaten bulbs and the remains of young plants often are the only signs of squirrel visits. Squirrels will also uproot small transplants and dig in flower pots. They appear to be especially attracted to corn in vegetable gardens, but also will damage tomatoes, preferring fruits which are beginning to ripen and often eating only a few bites before discarding a fruit and proceeding to find another. Their presence as unwanted guests in homes or other buildings normally is made known by audible rustlings and scratching.

Integrated Pest Management Strategies

Unfortunately, very little can be done to control squirrels, especially in areas where oak and nut trees provide a fairly predictable source of food.

1. Remove the squirrels. Squirrels can be trapped using live traps baited with fruits and nutmeats. If traps are used, animals should be released at a location at least 5 miles away. Check any traps at least twice a day so that any squirrels caught can be released immediately, and so that other animals such as birds can be released immediately. It is inhumane to allow an animal to remain in a trap without food or water for any length of time. Keep in mind, however, that other squirrels will move into the area in the absence of competitors.

2. Alter the environment. There is little to be done to exclude squirrels from gardens, because they can overcome all but the most complete enclosure. Placing such materials as hardware cloth on the surface of beds may deter bulb destruction, but such measures are far from certain and completely interfere with aesthetic considerations. Bird feeders should be placed far enough away from overhanging branches or structures to discourage squirrels from dropping onto feeders from above. Baffles can be placed around feeder posts. Many other devices of more or less efficiency are offered for sale by businesses dealing in bird feeding supplies. To keep squirrels from attics, seal the openings they use for entry and exit. If the animals are a persistent problem, a professional exterminator may be required to solve the problem.

3. Repel the squirrels. A number of formulations, available under several trade names, are sold to repel squirrels. Nearly all of them include some version of capsaicin, the chemical that lends "heat" to peppers. They all wash off in precipitation, so they must be reapplied as long as their repellent effect is desired. All repellents share one characteristic in common: they work for some gardeners in some circumstances, but are not 100 percent effective in all circumstances. When using chemicals, read labels carefully and follow directions completely.

Special note. Squirrels are managed and protected as game animals. Speak with local authorities or game officials before undertaking control measures involving trapping.