Here's an old post from Michael Bush. I used it and will continue to use it every spring. They love it! Make sure you read the directions through before you start so you get it right. The licithin disolves better for me if I use a whisk.
From an old beesource entry:
" 'Honey Bee Healthy' Recipe
5 cups water
2 1/2 pounds of sugar
15 drops each of spearmint and lemongrass oils
1/8 teaspoon lecithin granules
You have to dissolve the granules in very hot (almost boiling) water and let it cool prior to incorporating the oils into the mixture. The lecithin is an emulsifier and helps disperse the oils in the water mixture. This is the standard recipe according to a website article I read about using essential oils, and these are the two oils used in the HBH. I use less of the oils than the recipe calls for since I am feeding fairly heavily at this time, but for a spring or fall treatment, I will follow these measurements.
4518 Aurelius Road
P.O. Box 22009
Lansing, Michigan 48909
or toll free
or by fax
The last I purchased was Spearmint oil 1 ounce for $3.99
Be sure to mention that you are a Beekeeper to get the cheaper prices.
They seem to have it all in stock and a lot of great info on the oils used for beekeeping
"Everything works if you let it."