When you have invested a lot of time and money into your property, it is really annoying to have nightime critters dig up the flower beds or move in where they are not wanted.
For the last few years we have tried to make peace with the raccoon family that lives under the screen porch, but they keep digging up the garden and on occasion they let a skunk move in at the other end. I've chased them off for a short while with a sonic device but it has damaged MY hearing, not sure about theirs, and so I was still trying to figure out what to do. I refuse to trap them for the local wildlife rehab group tells me that the mom raccoon keeps the kids with her until she is pregnant again then she kicks them out, so there are always someone in the den, you can't screen it at night when mom is gone and know for sure that the kids are not inside. And trapping and releasing puts the critter into some other critters territory and they try to go home anyway and get hit by a car. So, convincing them to leave on their own is the kindest thing to do, so they take the kids with them.
In a catalog I found something called Night Guard, $20 + shipping from the manufacturer. It is a simple solar powered flashing red light that just makes night predators uncomfortable, so that they want to go elsewhere. Hey! It works! It works only on line of sight (about 30 degree spread), so you may need more than one. When I put one above the entrance they used to get under the porch, they did not come back in. They did continue to dig up the garden just around the corner, but not where the light was visible.
Says it works for owls, hawks, bears, coyotes, skunk, raccoon, cougars, and deer (but they are pretty smart so you have to keep moving it for deer). I can only say that it has worked for the raccoon.