Life goes on, praise The Lord.
   The use of screened/perforated boards was adapted into my research system
about four years ago.  The thinking in adapting this system was precisely to
remove dying mites from the hive environment. It was soon found to work and
implemented henceforth.
    Screened bottom boards also facilitate "drop-off mite counts" which are also
utilized for evaluation of the FGMO treatments in addition to larval counts.
Best regards.
Dr. Rodriguez