https://bip2.beeinformed.org/survey/ Thanks! I've been hoping to find this info...
...and in OH, people who DID NOT monitor for mites had lower losses (27%) than those who did monitor for losses (42% losses).
I am concluding that people do not know how to interpret what the alcohol wash, or sugar shake, or bottom board drops are telling them about the state of their hive.
It's one thing to say that about the sugar shake - notoriously unreliable, and about the mite drops - apparently just a reflection of brood rearing levels. But true for the alcohol wash as well? 30% losses for those who did use that technique. 41% everyone else. In OH. Maybe we're dumber than other states? Nah. It's true for all states as well.
I have come to a pretty big change of heart in how to interpret the alcohol wash numbers. For the months of April, May, June and most of July, I consider the alcohol wash numbers as only able to alert me to an immediately lethal mite level. They do not tell me about whether I have a potentially lethal number of mites, that will take my colony down by early winter. They do not tell me whether I should treat.
I came to this conclusion after playing with the Randy Oliver mite model. http://scientificbeekeeping.com/randys-varroa-model/
If you take any theoretical colony offered with the model, and ask, can I tell from the alcohol wash in April, May, or June if the theoretical hive will crash? Just try out that 1 question with changing the starting mite numbers in Jan in the theoretical hive. I found the answer was NO. Sure, mite counts in the theoretical alcohol wash went up from 0 to 1 or 2 as the number of mites in January were set higher in my theoretical hive, and resulted in a hive that crashed from mites. I don't believe that I will be getting an accurate reading with the alcohol wash during those months - it's too easy for a SINGLE mite to stay with the bees and not be detected.
I will be checking 2 times a month or so, starting towards mid July, and going through Sept. Those are the months with useful mite counts on the "curve" to a death spiral. I will be aiming for counts like 4 per 300 during that time - 3%, which is 9 mites, is too high for my goals.
This plan is in contrast to the standard advice, which is to check every other month, or now every month, and that the threshold is just 2% period, no matter the season. A hive with 6 mites in May or June will be dead before Sept. And you'll miss the upswing if you check the middle of august and then middle/end of Sept. This is true for the theoretical hive in the Randy Oliver mite model - and in my hives this year too.
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