“The best way to fumigate your car for spiders is to use peppermint or citrus oil.
Strangely (and creepily), spider infestations in cars are common. But never use a bug bomb or a fumigator in the interior of your car. They are flammable and toxic, and therefore pose safety and health concerns. While you can use a bug spray, these aren’t recommended either, as they also contain toxic ingredients.
Instead, go with a natural remedy. Mix peppermint or citrus oil (about 20 drops) with a quart of water in a spray bottle and spray it throughout the car. Spiders hate these scents and will usually leave the car as a result.