Usage: 

Oxalic acid can be used during all months with varied results depending on how much brood you have present in the hive. We have best results with oxalic acid when our colonies are just coming our of winter in early spring and in early winter. We are Maryland based so your treatment schedule may vary.

Weather you are brood less or not OAV is a device that is designed to be easy to use but you must not rely once on your success. You should always do a sugar/alcohol wash to check your numbers before determining if you have gotten a good kill. If you are in winter and above 50F And treating preform at least 2 rounds to insure good coverage / mite kill. Treating below 50F has been rumored to force the bees to break cluster and that's a risk I personally wouldn't take unless desperate but the goal is to be proactive so you don't have that high of numbers in fall anyways.

Currently the "Law" for oxalic acid is 1g of OA per box. New studies have shown that going as high as 4g per box does not negatively effect the bees though it is not approved for higher dosages as of yet.

In Conclusion.. Even with all current studies included you should be treating in a pattern or "Treatment" Schedule to be as successful as possible with keeping your bees healthy.