If you read this far, then you probably have some of these problems already. So, remove
the food supply. If it is a bird feeder, move it twenty or more feet from the house. Close
or cover garbage cans, and if possible make them inaccessible. If you have a barbecue near
the house, keep it clean and covered. Squirrels have been know to eat the drippings and
sometimes build a nest if they can get inside. It doesn't take very long, sometimes just
Maybe the squirrels are digging in your garden, or flower pots. While you can't stop a squirrel from digging, you can discourage it. Use hardware cloth, a heavy metal screening with a half inch square grid, to place in the flower pot. Cut it to fit around the stem of the plant, and extend it to the edges of the pot. Place it just below the soil. Put some small rocks near the edge to hold it in place. This same approach can be used in a small garden.
If the squirrels are eating your fruit as it ripens, about the only way to stop them is to cage the entire plant. Most times this is not practical, and allowing them to have a little may be a small price to pay. I know they can be wasteful, try to accept it as food tasting.
Other devices, such as high frequency sound emitters and animal scents may be effective for a short period of time. Once the squirrel gets use to them, and they will. They become ineffective, and you're out a lot of money.
The use of "Squirrel Away" or "Hot Pepper Spray" are also ineffective as deterrents. They can actually do harm to both squirrels, and other animals, especially when these products get into their eyes. Then how do you deal with a blind squirrel?
The use of "moth balls" as a deterrent does work. But again, only temporarily. A determined squirrel will get used to the smell, or simply push the "smelly stuff" out of its way. So if you do try this method, wrap them in a piece of metal screening to form a bag. Then tie the bag to a solid object, make it as difficult as possible for the squirrel to move. You will have to replace the contents every few days for it to be truly effective.
Another problem area can be exposed wires or rubber hose's. Most common are those on gas grills, and stored motor vehicles. But, low voltage lighting can be a tempting target for squirrels. What the most squirrels are trying to do, is clean and sharpen their teeth. They do this by biting through some material, (normally wood) then they pull their head back so the fibers slide between the teeth. I guess you could call it the squirrel version of dental floss. Most squirrels stick with small tree branches, but some have found the plastic coated wire or rubber hose does a much better job. The only way to stop this problem is to trap and relocate the offending squirrel. Once the squirrel is removed, the problem should end.
Once a squirrel has chewed its way into an attic or crawl space, again the only practical way to remove it is by trapping. Of course repairs should be made immediately to close the entrance hole. It is also important to cut off the access route to the attic or crawl space. This may require trimming tree branches that overhang the roof. Remove firewood that may be stacked against the building. Fill cracks in foundation walls. Even a one inch hole or crack can make a suitable entrance hole for a determined squirrel. When patching wood, use metal plates or flashing where ever possible. On foundations walls use concrete. Avoid plastic or PVC vents when ever possible.