I see that Sundance no longer sales Bt for treating comb, I wish him well. I have a question, though, regarding some Bt Agree that I bought from him back in 2011. I pulled it out a few minutes ago thinking I would spray some drawn comb with it and when I opened the ziplock bag a *very* strong smell hit me...reminded me somewhat of a poultry house with high ammonia levels in it. The powder had turned into a solid, but compressible clump. It had been sealed in it's original ziplock and inside of the bubblewrap mailing envelope that it came to me in. It was on the counter where I build my equipment so it wasn't in a damp environment though we do have high humidity in the south. The date on the envelope was in December of 2011, so that makes it 2-1/2 years old. I take it that it has an expiration date to it. Whatever the case, I won't be spraying this on any comb. Just thought I'd give a head'sup in case some one had some on a shelf for a while and was thinking of using it.