While camping one, time, forgot bug spray, and the mosquitos were picking us up by our ears and wedging us into trees to finish us off...the dogs, too!
Checked my plant book, an found that Vanilla Leaf, or Deer Foot (Achlys triphylla) had been used by the Indians to repel flies and mosquitos. Fortunately, there was tons of it growing around the camp, so I gathered a mess of leaves, squashed them into paste between 2 rocks, and slathered it on hounds and people.
Worked great! Mind you, we were -green-, but bug-free, and smelled nice, too....
Not sure if it grows outside the Pacific Northwest.