> I agree that a bottomboard under the screen would allow the fallen mites the
> chance to come back through the screen and re-attach to thier host, unless
> they are somehow trapped with a sticky board or other means.  Does your
> screen attach to a frame which acts as the bottom board or does the screen
> attach directly to the bottom of the hive body with a spacer allowing
> entrance on one side?
> Please advise

When mites are not attached to a host the distance they will travel is
limited. At EAS it was stated that the longest distance a Varroa would
travel was about 3/4 of an inch. If it does not find a host it stops and
waits, many times until it drys up and dies.