Re: Damaged wing?
Not sure how you did your count.
I do a sugar shake now. Find a brood comb and shake the bees off into a plastic container. Quickly scoop up 1/2 cup of bees and dump into a 2 qt Mason jar with the wide mouth. The lid on this jar is the normal ring and the middle part has been replaced with #8 hardware cloth. Put a big scoop of sugar on top of the screen and shake it down into the jar on top of the bees. Roll the jar around in your hands for a few minutes and then shake out all the sugar into a bowl. Add water to the sugar and start counting.
Below 10 mites I don't treat. Above 10 I know it is needed soon. Above 20 I treat immediately.
Dump the sugar coated bees in front of the hive.
Raising Vermont Bees one mistake at a time.
USDA Zone 5A