As with most rodents, ultrasonic devices are often touted as a squirrel repellent. They’re often hawked to repel pretty much any type of rodent, and to an extent, they do work. The biggest issue with these devices is if you have them outside, they need batteries to work. Their range also isn’t very impressive. Stick them to any trees in your yard, and they might do a decent job of
keeping the squirrels away, especially with a flower garden nearby.
Squirrels can be more trouble than people realize, and keeping them out of your yard is no mean feat. A lot of the repellents on the market are of limited range and use, but combined with other methods and strategies, they do have their use. Make sure to review your decisions wisely, otherwise, your yard will be full of ineffective repellents and gloating squirrels.