> do you have any method to relate the 3 day mite drop numbers to the > average number of mites per bee for the colony ? The mite drop numbers > will depend greatly on the size of the colony whereas they should be > independent of colony size for the sugar roll or alcohol wash methods. Good points. Any time I checked natural drop against the wash, I have seen "good enough" correlation. Personally, I just use 100 days for an estimated varroa average natural lifespan and estimate the colony population by looking at the frames of bees and considering the ambient temperature and did a little math. It helps to know how much brood is in the colony, and whether they are cleaning out drone brood as well as other things which might affect the drop. I discussed this on Sept 26, 2009 at http://www.honeybeeworld.com/diary/2009/diary092009.htm and other places on my website, since at one time, when I was running thousands of hives, it was my sole monitoring method. I think the most important thing to keep in mind is why we are estimating the varroa load, and what accuracy we actually require. For my personal purposes in my own yards, I am just looking for potential disasters and plan to use oxalic on all. A formic flash treatment or two might not hurt either, but I have not done that for years. I like drop boards simply because they show that mites are dropping and are another way, along with eyeballing bees for DWV and riders, to keep an eye on things non-destructively. As mentioned before, the Apinovar bottoms look to me to be a very elegant solution for the small beekeeper. The links below have some good info. http://www.apinovar.com/ http://www.apinovar.com/articles/FAQ_APINOVAR_en.pdf *********************************************** 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 Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm