Effective fly/insect repellent

[u/daithi_zx10r]

Hi all, just wondering if anyone knows of an effective fly/insect repellent, the last few times I've gone up to Glen Barrow we've been absolutely swarmed by flies for a high majority of the walk to the point where it would nearly put us off going, constantly having to fish them out of our ears and everything, so it would be amazing if anyone had any input as to what we could use that would work, cheers!

[u/strictnaturereserve]

smidge is good