"I hesitate to mention this, but there is an herb that seems to have insect repellent properties. Cannabis Sativa, or wild hemp, grows in clumps to a height of 3 to 12 feet. Cattle sometimes seek it out and lie in the shade of its thicket to escape the pestering of flies. Since the cultivation of this plant is frowned upon by some governmental agencies, it is probably best not to rely on it as your sole means of repelling flies." 1971 July August/Common Sense Control of Insect Pests: http://www.motherearthnews.com/library/
on a side note, cannabis is naturally very pest resistance, so growing hemp on farms would drastically cut the volume of potent toxins entering the environment and, consequently, our bodies.
Well out on the open range, where much of the U.S. cattle on the land roam, in the Dakotas, Montana, Wyoming, the DEA in their national drug report recognizes that hemp plants occurr in the wild as a result of the govermental plantings of hemp on public lands of the 1920s in aide of the war effort. If the deer don't eat it, and the bears don't eat it, then the cattle do love it for those reasons. There's too much land, not enough human resources to ever possibly get rid of the wild hemp growing throughout the U.S. there are so many MORE invasive plants such as Salt Cedar that cause real problems that hemp isn't even on the USDA's list to eliminate such as Canadian Thistle and other life suckers of that nature. Hemp is actually good for the soil, they recognize it and it's properties and leave it be. If it's growing wild, there's no problem. The actual anti drug laws fall under the Dept. of Treasury, not FDA or USDA, odd since it's a plant, but that just goes to show it's a political money thing.