If you have cars stored there, put some tin cans with one end cut off over the tail pipes, block off any air cleaner snorkels and close vents.
I like the old fashoned victor traps with the metal tab, not the cheese looking pad, bait with peanut butter, and put dry flour on a couple. Quicker than drowning.
Totally agree with blocking off the exhaust and intake. I remember one of my friends firing up his A12 car in the spring. It lit and then sounded 'funny' so he romped on it hard and it was normal. Went to the rear of the car and the quonset wall had the remains of dead baby mice and mice nest crap splattered all over the wall from both exhausts.
