I have been using screened bottom boards for about 10-15 years. However, I have noticed that the bees make their brood nest further up in the brood chamber. I am suspecting that the % of mites that fall thru the screen is a smaller % than that are chewed by the bees. Exactly what I have seen. Switched back 2 years ago. Charles *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html