I have some type of critter problem. I live in Southern California,in a
suburban area about 6 miles from the coast, near but not on a canyon,
and I have a fenced yard. Last summer something was gnawing my peppers
and eggplants-never saw what it was, and the amount of damage was no
big deal.

But now (I'm assuming its the same critter) this thing is decimating my
roses. It clips off the new growth, right where it is budding. It always
happens at night and whatever it is is very quiet. I've never heard
anything.

Last night I put plastic grocery bags over the smaller roses, which
discouraged our noctural diner and came out to a completely denuded Don
Juan. (Since it is more mature,+ too large to easily cover I thought it
was safe-WRONG).

no way is it bugs, it looks like someone went throught with pruners. It
is also not a deer, I think we'd notice one in our tiny yard, there is a
fence, and this is way too a suburban and area for that. So what could
it be? rat? possum? racoon? skunk? bunny? I've never seen any of these
guys around here, although I'm sure they are abundant (except possibly
the rats). I'm thinking possum.

Any suggestions for dealing with it short of borrowing a terrier?
Poisons are out, I don't like the idea and besides the neighbourhood is
full of cats, (who are clearly falling down on the job). some nice
organic deterrent?