I've been exercising and working outdoors all spring, in clouds of black flies, and I don't have a single bite. In a normal year, my face, neck and arms would be covered in red welts that itch and burn and swell, in spite of wearing long sleeves AND a ridiculous hat made of netting that the bugs always infiltrate. (Once you've got a black fly INSIDE your net hat, you're just a big meat sandwich to that little dork.)
But this year I've been using a Canadian homeopathic preparation called Mozi-Q (one small tablet dissolved under the tongue a few minutes before going outside).
I have no bites. They don't even LAND. Horse flies, mosquitoes, black flies, deer flies. Apparently it even works on lice and bed bugs. The homeopathic effect is so thorough that you'll think irrational thoughts like, "Well, maybe the bugs just aren't biting this year."
Then you'll make your friends try it. And when they come back to you and say, "My god, I don't have a single bite, even after gardening all weekend", you'll maybe start to believe it really IS working.
I've given it to 3 people besides me and they all said the same thing, "My god, I don't have a single bite!"
P.S. I've been using homeopathic treatments for 30 years and even took courses in homeopathy because it's such a fascinating and cool science. Homeopathic remedies are prescribed extensively in England by physicians. The members of the royal family are huge fans of homeopathy. You can read about the origins of homeopathy in the lovely little book, "Heal Thyself" by Dr. Edward Bach. (available as a free PDF)