Menthol crystals are the same ingredient found in candies and cough drops. Menthol is derived from a plant, making it a natural alternative to chemical miticides. Prepackaged bags containing 1.8 ounces of menthol crystals are available from your beekeeping supplier.
Place a single packet on the top bars of the brood chamber toward the rear of the hive. Setting the packet on a small piece of aluminum foil prevents the bees from chewing holes in the bag and carrying away the menthol. Bees are tidy and try their best to remove anything they don’t think belongs in the hive. Leave the menthol in the hive for 14 consecutive days when the outdoor temperature is between 60–80 degrees Fahrenheit. The menthol vapors are effective only at these temperatures.