[LAlldredge]

Since we're in that mite danger zone I thought I'd offer a link to Randy Oliver's varroa monitoring page. He has an excel spreadsheet that allows you to add a certain amount of variation and model mite treatments. Math can get wonky but really like what he's getting at. Essential for new beekeepers as they work out their mite strategy.
http://scientificbeekeeping.com/randys-varroa-model/

Download link is on that page.