I have 8 hives, with one hive having high varroa counts. In Aug., the count was 5, so I started weekly OAV, for 4 treatments. I was unable to repeat the count, after treatment, until middle of Sept, and the count was 15, and started 3 more OAV treatment. My count last week was over 25!!! Yicks, I have never had such a high count. I gave that hive a formic acid treatment, and have now treated the other hives, which have between 1-6 mite counts. Is the hive worth saving? I have read that some BKs cull hives that have counts over 15. Also, does OA loses its potency over time, my package of OA is 5-6 years old. Thanks for any advise.