If you don't mind the smell of natural gum turpentine, it's been working great on mosquitoe and black flies here in the north west ontario deep woods. A dab of the turpentine on a rag clipped to my hat allows me work in unbearable conditions. Place rag in sealed bag and reuse numerous times. A turpentine essential oil should work the same.
Well since this topic is in the survival forum, this might not be too gross. If you ever crushed a millipede you would know how terrible it smells. Disgusting. Funny thing that mosquitoes also think the same Well in my experience at least. Crush one and wipe it on your ankles => no bugs. I personally prefer to wipe it on my socks/shoes. Keeps bugs away, cats etc. away. It lasts for 45 mins. In very desperate situations wipe it on your neck. Soon your nose will ignore it..
Edited to add: not all species are suitable (I don't know which ones though), and some can cause allergic reactions.
Where I live all you need to do is find a beauty bush, grab some leaves, crush them in your hands and rub on your skin and or clothing and you are done for a few hours. No bugs of any kind, not even ticks.