I carry three types of insect repellant - natural (bog myrtle), 50% DEET, and 100% DEET.
In Scotland I only ever need the bog myrtle but where there are mossies (as opposed to midges) I have to move on to the DEET, especially anywhere that malaria may be a problem.
I suffer badly when bitten by midges - each bite swells up and is unbearable, but the bog mytle extract works well for me. However, I think that's the problem, some repellants work for some people and not others.
But, if you've ever read Wolf Totem, you'll realise we have it easy!
Cheers,
Broch