Something in your rig is attracting them. Many years back we have friends with this issue and it was the coating on the wires. Turn out it was made out of some plant stuff. They are no longer here so can't ask them. Add sticky traps to your list. Try spraying the peppermint oil in the engine compartment if not flammable but keep of wires and hose. I have tied a bag full of cotton balls soak in different thing. Some they took the bag others they eat a hole or did not mess with them. Sorry too long ago to remember them all. The peppermint was for sure one they did not mess with.
