Tried this on the Isle of Mull a couple of years back and did not find it very effective.
There was a party of Americans beside us and they had five jars of the stuff and were very
badly bitten. We heard later from someone that the recipe had been changed and it was no longer effective.I think that midgies and flies are attracted to some peoples feromones
more than others, and also if you perspire a lot. I have been on the hills and been completely free of flies then someone would pass with the most awful swarm of flies around them . and sometimes some of them would transfer to the party I was with.
I now try to contain my west coast of Scotland trips to outwith the main midge season.
Going before the end of May or into September, when they are beginning to die off for the winter. If the weather is warm and damp their season can be extended.
Ithink that various anti midge products work differently on different people. I am recently informed that eating a lot of garlic helps but havent tried that yet. May keep friends away too. LOL.