Colonies started from
local wild swarms have been honed by natural selection, and will have very high survival rates. My hives coming from local swarms ONLY, had zero losses this winter (but it could be 10% to 20% depending on year). My apiaries are completely treatment-free. A treatment-free friend beekeeper in Kansas with 137 colonies (all coming from local wild swarms genetics) only lost 2 hives. If you want to understand why swarms survive much better than package
bees or nucs, I highly recommend Dr. Tom Seeley's
The Lives of Bees (it's based on his 40 years of research of wild honeybees, and lessons for beekeepers - for example, Seeley found that the
average lifespan of wild colonies in upstate New York is more than 6 years - without any treatments, of
course - so if you tap into this survivor genetics, your results will be very different from buying commercial bees with low disease resistance).