>Not in my experience, have seen them rushing from one side of a frame to
>another, and always been amazed at the speed they can travel. What I think
>might have been suggested is the depth below the frame where they cannot or
>will not climb back up, but I thought that was more than 3/4 of an inch.

The way it was explained was that once the mites start looking for a host
(questing) they will only move about 3/4 of an inch. Perhaps these mites are
not looking for a host, but searching for a suitable brood cell, or just
running from the disturbance. Even so the distance a mite would have to
travel to get back to a bee after going through a screen insert would be the
distance across the bottom board plus the distance up the side.