I don't know if you have them in Idaho but if you do try a Hedgeapple or Osage Orange. Cut in half. lay on a pie tin or something similiar and put in the vehicle. Supposingly where hedgapples are mice and spiders don't go. If you are not sure what a hedgeapple is do a search and you'll get a lot of hits. They are about the size of grapefruit, light green, and bumps/warts all over them. DO NOT eat them.