My Crimean beek friend has mentioned this several times as a practice in family lore.
Lazy Mountain, AK
"Family lore"? Varroa has only been a problem in Europe for like 30 years, no?
Assuming we're talking about ROPE hemp (duuuude....wait, what?), I suppose it would be worth doing some experiments - but hemp rope in the US is likely to be treated with some kind of preservative to delay rot or what-not, and I'm not sure what effect burning such a chemical might have on the bees themselves.