I don't remember where I got a whole bunch of RV tips, but these relate to pest control and may be helpful:
Moth balls in pantyhose hanging inside engine compartment to chase off rodents.
PineSol mixed 50/50 with water to spray and clean all surfaces to chase off flies.
Dog flea collar cut in pieces to keep in propane compartment to chase of wasps.
Irish Spring in outside compartments to chase off mice.
Vensmile
12v under hood ultrasonic animal/rodent deterrent (yes, I know there is redundancy in some of these items.... but no flies/rodents/wasps....)