Answer: Chipmunks can damage stone walls and patios by undermining the underlayment as well as eating a number of plants. Their population tends to be cyclical, in that it peaks and then naturally declines again. Here is a discussion of this you may find interesting.
You may find the following information helpful in terms of controlling them or limiting the damage. Although it mentions mothballs, these are not recommended for use outside.
I hope this helps.
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