Found this info on the web, so... experiment, but trust only in your own results.

Here are 5 essential oils that repel bugs.
1. Lavender This smells sweet to us but bugs absolutely hate it. It works on mosquitoes, flies and other insects.
2. PennyRoyal this is a member of the mint family and it is toxic to insects.
3. Lemongrass This essential oil comes from tropical lemongrass and has a citrusy sent. It is a natural flea and tick repellent and can be sprayed directly on the skin.
4. Eucalyptus use this alone or along with citronella oil to keep bugs away. According to the Journal of medical entomology, Eucalyptus extract can reduce tick bites and infections.
5. Lemon some lemon essential oil can work against fleas and other bugs. Slightly dilute it and spray it on your clothing and skin.