A tight weave fence fabric buried 1 foot deep and bent inot a reverse L (_:) should work, but it does need to go that deep and also needs to be at least 1 foot by 1 foot to discourage those buggers. I have not found anything that is a good deterent if those buggers are bent on occupying that burrow.

Do you have any teenage boys? Buy them a .22 and you should be in good shape

We had 1/2 inch mesh down to 15 inches, and the squirrels went under. I'm not going deeper. Mesh doesn't work.

There must be some chemical/other deterrents, though. Surely someone here has tried Deerscram, or some such?

Cayenne?

Bubble gum, glue traps, or some such?

patty, I really don't think anything will keep them away. They are like rats, nothing bothers them. Eventually snakes will move in, that might help a little. If you really want to be rid of them you will have to shoot, trap, or poison them.

Try snake or cat poop tossed around. Rodents fear the unseen predator. I've used my pythons manure for over 20 years as a casual mulch additive. Squirrels and bunnies enjoy the yard but seem hesitant to enter the gardens.

We have had a major ground squirrel problem for the last couple of years .
Shooting works if you have just a few, bubble gum maybe does the job, but we cleared 80 infested acres with anhydrous Ammonia ( it is not organic ) It took us 14 days to complete but I think we killed about 90% .
We had so many that people and cattle were getting hurt by stepping in the holes, and the badgers came after the ground squirrels with even bigger holes .
Now we are waiting to see how our actions impact the rodent population next year .

ONE NOTE of CAUTION : Anhydrous Ammonia is dangerous!!!!, very much so and it is hard to get, due to all the terrorist treats .

Hmmm.

Any details on application method?

I assume this is not organic because it is so toxic. Yes? But it sounds like the sort of compound that would wash away quickly and/or break down .... might even be a nitrogen source for some organisms? So it might be at the less offensive end of inorganic methods?

One problem with fences and mesh is that the critters will just climb over them, rather than go under them. There are several limited application rodenticides that will work to kill the squirrels; in our state you need to take an hour course to be able to get them. The state provides them for essentially no cost; them want to help control problems. The problem with these materials is that some can be quite dangerous to other animals that you don't want to target. The courses basically help you understand how to apply the material safely. Hav-a-heart traps work like a charm to catch squirrels. They seem to line up to get in, and don't seem to learn from seeing their friends inside. I recommend that you not leave the bodies around to discourage others; squirrels stink like crazy while they rot, and they are not consumed by many of the birds that eat other dead animals. After a few months of catching squirrel a day, you may get to the point that you have to wait a couple of days to get the next one. The trapping can make a difference, but will not eliminate the problem.

Renais