Tracheal mites can be a very serious problem for your bees. They are tiny, microscopic mites that attach themselves to the trachea (the breathing tube) of the bee. Since they are microscopic, it is hard to know if your bees have them or not. One way that you might notice your bees having tracheal mites is if you see an unusually large number of bees walking around the front entrance of the hive (although not during weather that is very warm or during the swarming season). The tracheal mites not only obstruct the airway making it difficult for bees to get oxygen, but they also will start to eat the inside of the trachea causing scratches within the tubes.
A very effective treatment for tracheal mites is the use of menthol crystal (brand name Mite-a-thol®). Mite-a-thol® is 99.9% pure L-form menthol crystal pellets. When used properly, it can kill up to 97% of tracheal mites. To use, place one 1.8 oz. packet on the top bars of the brood chamber (if you have more than one brood chamber, place on the top bars of the uppermost box). Leave the treatment on for at least 28 days, but not during the honey flow. Daytime temperatures must be above 70 degrees F for the most effective results. Treat both in the spring and fall, allowing at least 14 days between end of treatment and honey flow.
Note: Store Mite-a-thol® pellets in a cool area, ideally in a sealed container in the freezer.