This is somethng I saved and it is from the well known Michigan herbalist Joyce Wardell. Marianne
Here in Northern Michigan, we also put in our claim for the mosquito as state bird! Mosquitoes are first attracted to heat, second to Carbon di-oxide and lastly to lactic acid. When they sense all three, they know they have a blood target. The most effective natural defenses either mask your heat, lactic acid and Carbon di-oxide, or make a barrier.
Mud is the most effective, but socially questionable. But many times when I'm out gathering, I'll smear mud on - not only does it prevent the mosquitoes from being able to bite you - it's soothing and cooling to the skin and masks your scent providing better opportunity to see the fauna as well as flora.
Smudge pots - punch a few holes in a coffee can, put some hot coals in the bottom and burn small amounts of green cedar or damp leaf debris for smoke. Excellent if you know ahead of time you're walking into a swamp at dusk - but must maintain your smudge pot.
Smudge sticks - wrap dried aromatic herbs in a tight bundle with thin wire, or string light and let smoke. Lavender, rosemary, yarrow, cedar all work great. I sometimes wear them in the back "pocket" of a baseball cap.
Crushing fresh aromatic plants and rubbing them on your skin works only for a little bit - BUT if you crush the plants, then sit very still, not quite next to someone who is busy swatting mosquitoes - the mosquitoes will target the other person who is releasing more Carbon di-oxide and lactic acid into the air than you are. Sneaky, but effective.
Eating sources that are rich in B vitamins seems to help (helps inhibit the build-up of lactic acid, I believe) thus the brewers yeast defense - plantain seeds were used here.
I've tried lots of EO singles and blends with pennyroyal, lavender, citronella, rosemary, eucalyptus, peppermint, etc. I find them more effective against black flies and gnats than mosquitoes.
Just a note: the Anishinaabe work for mosquito is skee-kee-mahg - which is actually mosquitoes. There is no singular word for mosquito - because there never is just one, you know.
JoyceW