[Oldtimer]

Some people have done it with mixed results.

Problem being the TBH design is not well suited to distribute the vapors properly. Usually a fair bit of empty space in the average TBH, plus the top bars being joined together is a major problem.

A non vapor treatment such as apivar strips, which can be hung between combs and spreads by bee to bee contact, is ideal for TBH's.

 

[GregB]

I don't know much of treating the bees - disclaimer.

But IF a TBH has dual entrances at both ends, why not use some forced air movement (apply the med at one end - slowly suck the air from the other end - that should pull the vapor/gas through the entire long hive).
Say, you notice that med started exiting from the entrance where you pull the air out - this means that the med has filled the entire hive volume - you now can stop pulling.

I don't know of the workable implementation of this or even feasibility.
But the idea seem logical to me - assuming dual-entrance TBH OR an asymmetric entrance (then you can create a hole at the opposite end and do the same pull-through process).

 

[AvatarDad]

No. Not really. (Not in my experience, anyway). Oxalic is probably the easiest treatment to use (yes... I know it is less effective in summer). Here's a little article from Randy: http://scientificbeekeeping.com/mite-management-in-top-bar-hives/

 

[warp1]

Great link....I missed Randy's article while surfing his site in the past