In researching local bee organizations, I stumbled across information on experiments that used essential oils like wintergreen, spearmint, tea tree, and patchouli to combat varroa mites in bee hives. The varroa mite problem is one of the main reasons I didn't start beekeeping several years ago.
So I was really excited to learn about the essential oils remedy. We use tea tree oil a lot on ourselves. Most recently we tried it on Emma's thumb when she got stung by a bee. She was trying to get a picture of the pollen sacks on the bees' legs. They did not want to be photographed. Anyway, tea tree oil didn't help in this case. Neither did holding a penny on it. She read that toothpaste would help, but she never tried it.
The essential oils treatment works by feeding the bees a sugar syrup with the right essential oil. It is left at the entrance to the hive and is eventually passed on to the larvae by the nurse bees. It doesn't hurt the bees, but it disrupts reproduction in the mites.
There is another method whereby the mites are killed by direct contact with the oil. I didn't read up on how that is done.
Some researchers at West Virginia University came up with their own essential oil mixture to feed the bees. They used lecithin as an emulsifier to mix the essential oils thoroughly with the sugar syrup. If the oil is not mixed well, it can kill the bees. They determined that spearmint worked really well in reducing parasitic mite sydrome, but the bees didn't find it tasty. Experimenting further, they hit upon adding lemongrass oil to the oil of spearmint and syrup. I'm guessing the lemongrass oil masks the spearmint flavor. Their recipe is called Honey-B-Healthy. Here's a link to the information. http://www.wvu.edu/~agexten/varroa/honeyBhlth.htm
For more information on the Varroa mite, here's the entry from Wikipedia:
Varroa destructor can only replicate in a honey bee colony. It attaches at the body of the bee and weakens the bee by sucking hemolymph. In this process the mite spreads RNA viruses like Deformed Wing Virus to the bee. A significant mite infestation will lead to the death of a honey bee colony, usually in the late autumn through early spring. The Varroa mite is the parasite with the most pronounced economic impact on the beekeeping industry. It may be a contributing factor to Colony Collapse Disorder (CCD) which is threatening hives throughout North America.
I have never done much research into using essential oils for human healthcare, but this information on how it is helping the bees prompts me to start.