Formic acid varroa treatment
With the honey top box removed, a plastic mesh covers the top bars, then over this goes the inverted clearer board. On the wire a kitchen towel soaked in formic acid, and on top of that to prevent evaporation into the quilt, a piece of impermeable plastic held down by the quilt. On top of that the normal Warré cottage roof.
On many of my Warré hives there is reasonably airtight space below a varroa floor with rear access for feeding and flash formic acid treatment from below. This particular hive had an early prototype floor, and although suitable for varroa checking under the screen, is too open for treatment from below.