Mite-Away II® is a formic acid treatment for the control of varroa and tracheal mites. It should be used as part of an integrated pest control management program. DO NOT APPLY WHILE HONEY SUPERS ARE ON. Allow at least 2 weeks from treatment before placing honey supers on the hive.
One single application pad can be used to treat 6-20 frames of brood. A 1 1/2 inch spacer rim and two small spacer sticks are required. To apply you must place the pad on top of two spacing sticks which go on top of the brood frames. Place the pad with the holes facing down to help the formic acid circulate throughout the hive. All holes in the hive must be sealed except for the bottom hive entrance, which must be open during the entire treatment. Mite-Away II® should be used when the day time temperatures are in the range of 50-79 degrees Fahrenheit. If daily temperatures exceed 82 degrees Fahrenheit in the first seven days of treatment you must remove the pads. Store pads in original container until heat wave is over. Treatment of hives when temperatures exceed 82 degrees Fahrenheit can cause major damage or loss of colonies. Brood mortality may occur for up to 14 days during the start of treatment with brood rearing returning to normal after treatment. 

This is a very dangerous chemical:
Safety equipment must be worn when treating with Mite-Away II®. Read all safety manuals prior to use. Do not wear nylon suit or jacket or coverall when using Mite-Away II®.