I used Apiguard last September got the full course done on one, but only half on the other because that colony's numbers stayed low the longest. (And of course for the third, the one that never had a brood break, that colony's numbers were low, stayed low, kept low all winter, and remain low, often one or zero/day.) (No damage to either colony treated, I had no winter losses.)
And I monitor a lot, even though lately in the midst of my anti-swarming efforts that part has had somewhat short shrift. Luckily the colony that has had the most anti-swarming divisions is the one with the biggest mite load, the mites are hopefully being suppressed by my splits from splits from splits "management" decisions. But I need to get back on the stick with my sticky boards.
Regarding how mites may sense swarms and begin ramping up production which presumably could increase phoretic loads that travel with the swarmees: so then my bees undoubtedly have brought mites with them on arrival last spring. Can't argue with that. But after they were here they experienced the brood break when we cut them out of the walls.
(And in my equipment planning over the winter I made sure to add a screen bottom board/sticky board to the list for every expected split and a few extra on hand in case I got new swarms to my barn walls. None so far, which is good since I'm at my hive-limit anyway. But if new bees arrive, they can expect to get monitored and treated, if necessary. I would not allow a feral colony to be that close to my now-managed hives. Bad ju-ju, I think.)
Mites may also just be opportunistic and as the conditions and decisions within the hive shift over to increasing colony size in preparation for swarming they simply have more brood to parasitize and so their population grows along with the bees. I think the biggest risk for developing huge mite problems is actually later in the summer when the bee population begins to decline but the mites are just getting ramped up. Then the relative level of parasitization can get really out of whack.
Since I got all my bees from self-presenting swarms I have no knowledge of their genetic make-up. Perhaps they are from a "survivor feral population" whatever that means.
I rely on sticky-boarding as a continuous monitoring tool. And I treat when they reach the NYBeeWellness and Ontario TTTeam thresholds. But I am careful to avoid treating a hive that doesn't get there, which is why one of my three is still TF.
I was only moderately impressed with the Apiguard. It reduced the daily mite drop numbers, slowly, but I saw no big mmite fall on the boards. I bought, but too late for use last winter, materials to use OAV-ing during the broodless period. I also bought some MAQS (but have not used it, yet) when the mite numbers on my biggest hive (the one I've been steadily splitting into pieces over the last few weeks) started to climb a bit this Spring. One possibility to use it might be in the way suggested by MDAX above: using half strength application to kill only the phoretic ones after a brood break to clean up the ones still in the pupa. (Unlike Apiguard which ran into too-low temps for efficacy last Fall, MAQS has a high-temp limit (80 F) for safety so that makes an important consideration for summer use, perhaps that's the source of reported queen problems with it.) At any rate, at the end of the brood break ALL the mites in the hive would by definition be phoretic and so vulnerable to any treatment that smacked down that life-stage, even if it would otherwise be less-than-effective in cleaning up non-phoretic mites. Timing would be crucial there, especially with a new queen just on the cusp of laying.
All of my hives have unlimited brood nest since I don't care where the brood is. I have both foundationless (starting this year, not last) and a mix of Pierco plastic frames, Pierco foundation and tons of tied-in old comb that came from the historic feral nests in the walls. (They don't like that old comb very much, however. Their "best" drawn work is on Pierco plastic frames and, lately with foundationless.)
I am not really convinced of the efficacy of "small cells". My bees are all naturally smaller than I see in the hives when I go hang out up at Betterbee's apiary. Their bees all look much bigger than mine. When I looked at their nucs and packages this Spring, I worried that my bees were somehow undernourished, puny things, but mine seem to be doing just fine, so I'm crossing that worry off.
I guess my point is that even (some of) my small-sized bees, despite being so-called regressed in size, if not any other way, got mites and needed treatment. Which I provide because they are in my care, not because I like doing it. The only mite approach (whether TX or TF) that I can not support is routine, repeated treatment in the absence of any effective monitoring program. I know from my life-experience in agriculture that leads to loss of effectiveness and paradoxically makes pests harder to control.
And like my query to Wolfer, above, always interested in what techniques you use to avoid swarms. No sooner did I wrestle them trhough the Winter From Hell, than this new challenge arose. It's always something!
Enj.
