Sugar roll as Dawn said
I use OAV and nothing else these days.
I posted this elsewhere just now
You can vape with supers on if you really have to.
Move hive aside, lift super onto a new bottom board so that returning foragers have somewhere to return to.
Seal entrance to brood box/s and vape.
When finished rebuild the hive as it was. The bees move the oxalic about so those in the supers get a dose
You can get into quite a rhythm with it and if you have an assistant it’s a doddle
This question of mite resistance comes up frequently. There is no evidence that resistance to oxalic is occurring as the damage is a physical one to the mites’ structure.
There is another way of measuring the colony’s mite load and that is with an accelerated mite drop. You treat the whole brood box with something that dislodges all the phoretic mites and you take a 24hour measurement. The traditional method is to dust the bees with icing sugar but you can do it with oxalic vapour. I do that and it’s so easy, you don’t have to open the hive up as you would with sugar dusting. I do it this way when there are no supers on. Anything over 20 gets treated