" some brood does get killed but a lot less than using both pads. "
So you think they'll be plenty of brood left to split at the end of the seven day treatment. Or will that add too much stress?
since they tell you not to go into the hive while the pad is on, all I can say is that when I put the second pad on all I found was sealed brood and eggs so the queen had started laying again, but the eggs and maybe some of the lava were killed, I also put them on three deep hives with honey supers on, so your results may vary and your temps. are probably higher now then my temps were then. Off the top of my head the way I had it figured, they say that 85 % of the mites are in sealed brood, there is no claim that the one strip has enough acid to kill the mites in the capped brood(but it may), the pad only puts out a lot of acid the first three days, so one pad would kill 15 % of the mites plus the mites that hatch out of the capped brood for three days, so that three days may be as high as ? 25% of the 85% more. so best I could hope for with one strip would be 40% of the mites killed with one strip.
The stuff I have read, and from the time I used it says that if you have really high mite counts, its not as effective. The way I had it figured, with the second pad going on at day 13, I should get as good or better mite kill as putting on both pads at the same time. The mite count to start on my hives were amazingly high, high enough that I brought a sticky board to the beeks meeting and one guy said "when did the hive die", after the two treatment I still had to treat with apiguard after as the mite count was still to high.
on a side note all 12 hives in the apiary are still alive and kicking as of last weekend, much to my amazement.
I would still opt for using apiguard in the spring as it doesn't set the hive back enough to notice, that's what I do unless it doesn't warm up enough this year to be effective.
the only way you will find out is try it on one hive, go in on the 4th day and see how much brood you have lost. but if you have really high mite counts you may not have any choice.
you will have plenty of sealed brood left, you may not have much open brood left, but since you are making splits and putting new queens in you may not want open brood in it, less chance of rejecting the queen. Some hives seem to get more stressed when you put the Maqs on than others, at lower temps they don't seem to react as much. good luck, let us know what you decide and if you decide to test it what you see.
here is an old article that originally came from the people that now make Maqs, article was about Miteaway II but the numbers should still be relevant. what this says, if you kill 50% of the mites, it only buys you 3 weeks. if the link doesn't work I won't be terribly surprised but let me know and I'll try and fix it.