In mangrove swamps crushed up mangrove tree leaves rubbed on the skin do work in a pinch.
We used to go to a surplus store and buy little green bottles of a white thick liquid bug repellent. It was ex-military and quite strong...stung the eyes too if you got it near them.
Oh...and when we had an old TE Cortina and went out crabbing, I sat the bottle on the boot lid. It fell over as I was wiping the stuff on my arms, and a line of it dribbled down the side of the rear quarter on the white paint. I left it there for a while until I finished applying the stuff. Then I wiped it off the panel with a finger.
And it took the top layer of paint off...
Strong stuff...
