I put in new landscaping , 15 boxwoods and Golden mops. Everyday a new attack by chipmunks, digging deep under them, and I'm guessing eating the roots and nesting. After reading about sonic devices and toxic products, I found an article about moth balls. I bought a box of them at Home Depot. I'd roll a couple down each hole, and push the mulch, dirt and rocks back down into the hole. The next day, there's be an exit hole, and another plant would have all the mulch dug away, and another deep tunnel. I'd roll 2 or 3 more moth balls down that hole , cover up and wait. After about 5 days, and 6 of my 15 plants were under siege,they gave up. I still see them all over our neighborhood and they are constantly around my block retaining wall, but it's been 5 months and not one plant has been touched and the moth balls didn't do any damage to the boxwoods and Golden Mop plants. They took great and are very healthy.