Many threads at many beekeeping websites and blogs cover essential oils in all sorts of combinations. Do they work? Well, I suppose it's all about what the goal is. As MB in the post above states, some are anti-microbial and anti-fungal. Well, that's the EXACT point if you're trying to deter chalkbrood or mold growth in something like thin syrup. Of course the mites don't like it either, but it all comes down to dosing and study. As far as that's concerned, there's no study out there to confirm that spraying thyme oil on your bees will keep the mites at bay. But, as a lot of other things, many have claimed
on message boards
to have "cracked the code" with essential oils....
Randy Oliver has written on thymol and what not at his blog www.scientificbeekeeping.com
. It's worth a read!