Squirrels sometimes cause damage around homes and gardens, where they feed on immature and mature almonds, English and black walnuts, oranges, avocados, apples, apricots, and a variety of other plants. During ground foraging they may feed on strawberries, tomatoes, corn, and other crops. They also have a habit, principally in the fall, of digging holes in garden soil or in turf, where they bury nuts, acorns, or other seeds. This caching of food, which they may or may not ever retrieve, raises havoc in the garden and tears up a well-groomed lawn. They sometimes gnaw on telephone cables and may chew their way into wooden buildings or invade attics through gaps or broken vent screens. Tree squirrels carry certain diseases such as tularemia and ringworm that are transmissible to people.They are frequently infested with fleas, mites, and other ectoparasites.

Biology and Behavior

Tree squirrels are active during the day and are frequently seen in trees, running on utility lines, and foraging on the ground. Tree squirrels are easily distinguished from ground squirrels and chipmunks by their long bushy tails and lack of flecklike spots or stripes, and the fact that they escape by climbing trees and other structures. All are chiefly arboreal, although the fox and western grey squirrels spend considerable time foraging on the ground. Tree squirrels do not hibernate and are active year-round. They are most active in early morning and late afternoon.

MANAGEMENT

In urban and suburban areas tree squirrels are difficult to control because of their great mobility and because many people feed and provide nest boxes for the squirrels in order to encourage their presence. It is relatively easy to keep squirrels out of buildings, but keeping them out of a yard or garden is a continuous challenge.
Monitoring Guidelines

The detection of tree squirrels is fairly easy because they are active during daylight hours and are highly visible. If tree squirrels visit your garden or yard on a regular basis, it is likely that damage will occur at certain stages of crop development, particularly with fruit and nut crops. If squirrels are seen in your trees, some kind of preventive action should be taken; squirrels can strip a tree of its crop in a short time.
Habitat Modification

Trees that overhang roofs or are close to telephone lines should be cut back to slow the movement of squirrels about the yard. Anything that can be done to make a garden less attractive to squirrels is helpful.

Screening or blocking all potential entrance sites such as small gaps under the eaves, overlapping roof sections, and knotholes, can prevent tree squirrel access to buildings. Because they often travel on overhead telephone lines, power lines, and fence tops, they frequently find entrances at about these heights. When even a small opening is found, they can enlarge it by gnawing. In the absence of an obvious entrance, they can gnaw and create an entrance into an attic. Sheet metal or 1/4-inch wire hardware cloth are suitable materials for closing entrances.