I posted here 2 weeks ago about the damage squirrels caused to my truck, first chewed through a rear shock wiring harness then part of the wiring harness under the hood, a wheel speed sensor effecting the ABS and a hose going to th front hubs. They built 1 nest overnight against the passenger firewall, I cleaned it out, 2 days later, another nest in the same spot. It cost me $1000 in repairs. Here is what has worked for me so far. 1) i sprayed isopropyl alcohol under the hood (cool engine) where the nests were to kill their scent. 2) I tied a bundle of 12 drier sheets in the same area that I'll replace every 2 weeks. 3) I installed 2 ultrasonic pest devices that also have a series of flashing LEDs under the hood. 4) I have 2 empty cool whip containers, one under the oil pan and one under the rear end half full of Pinesol and alcohol in the center line of the truck that I park over.. Alcohol keeps it from freezing and the stuff is very pungent. 5) I have 4 live traps around my truck that I'll keep there over the winter. So far I've caught 10 squirrels. I also keep the spray bottle of diluted Pinesol in the garage and give the area under the tires a quick spray every 2 days. Good luck