What possible evidence do you have for this? I have seen varroa crawling all over a table top, they can survive for days outside of a hive and I am pretty sure they can crawl back in from the ground.They are more mobile than is obvious when you first see them, but falling on the ground is a death sentence. They will not find their way back in.
Yeah, well, plenty of people don't know what they are talking about. 1) I doubt healthy mites fall off the bees very much. Mostly mite drop is dying bees. 2) Healthy mites can travel all over the place, either by crawling or riding on the backs of bees.Plenty of people seem to think that 3/4" is enough... and sometimes it seems it is, but I suspect SOME of those make it back.
No, how effective would depend on whether they crawl back or not. Obviously dead mites aren't crawling back up. If they are falling because they are already dead, that tells you very little.How effective a SBB is would have everything to do with what makes mites fall off of bees.
Well, I'd say if they are dead when they fall off that's a pretty good reason why they fell off, but point taken.No, how effective would depend on whether they crawl back or not. Obviously dead mites aren't crawling back up. If they are falling because they are already dead, that tells you very little.
What I meant was: you don't know if they died from old age or from some sort of behavior on the bee's part (or from some chemical, for that matter). The chief problem with mites, however, is reinfestation.Well, I'd say if they are dead when they fall off that's a pretty good reason why they fell off, but point taken.
Mite populations can increase due to the drifting of foragers from infested colonies or robbing failing colonies infested with mites. The extent that immigration affects mite population growth in colonies is not known. Mite migration has been reported to occur from heavily infested colonies that were 1.5 km away.
DeGrandi-Hoffman, G., Ahumada, F., Curry, R., Probasco, G., & Schantz, L. (2014). Population growth of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies treated with beta plant acids. Experimental and Applied Acarology, 1-16.
I sat in a UF seminar and the PHD said a UF study showed 14% fewer mites with SBB. Not enough to defeat the little monsters, but a step in the right direction. I use both. I prefer SBB with Oil trays to kill SHB, but they are expensive. I use my solids because I bought them first. When I buy new, I buy SBB, usually with trays. I'm trying TF with Beeweaver queens and SBB.Very interesting thread. I'm new to beekeeping this year, and unfortunately, i was in la-la-land and thought i wouldn't have to learn about mites until next year! Pffft.
Did i just read on this thread that screened bottom boards do NOT offer a significant advantage in dealing with mite loads? This would be a relief to me since i've been beating myself up over having decided on solid bottoms. Having just performed our first sugar dusting (pictures are at http://wabeekeepersforum.proboards.com/thread/1796/photographs-inspection-varroa-edition-photo) it certainly seems as if screened bottoms would have made the process a little easier.