Mouse Fortress?

[Funracer]

Just finished my engine beautification and performance upgrade project.
I do not want to go thru this again:
http://www.zr1.net/forum/showthread.php?t=19868

By the way, that is not the first mouse house I have cleaned out of my engine.

Not able to drive my car daily which is no doubt the best solution.

My wifes friend says to keep a box of moth balls in the engine bay, which
is cheap and low tech so that might be good if it works. Not sure about the
chemicals in moth balls.

Any other ideas for this common issue?

Thanks