If you're a bit creative, you could wire up an electrical rat trap - set up an RJ-45 socket to connect to an AC power plug, and another to connect to an AC socket. Plug a night light or something into the socket, connect a network cable of the flavor the rats have been eating into both jacks, and plug the AC power end into AC power strip. Rat chews on wire, gets AC power in mouth. Should stop them real quick, unless then can sense the signal difference before biting in ....
Fred Wagner
frwagne@longbeach.gov