Tracheal mites are microscope mites which reproduce in the trachea (airways) of the bee. A visual aid that would suspect tracheal mites would be a large number of bees walking about the outside of the hive.
The mites affect the bee in two fashions that limit the bees’ ability to acquire oxygen. The mites physically obstruct the airway. The mites feed on the walls of the trechea causing scarification of the tracheal tubes.
The traditional method of treating for tracheal mites is the use of menthol crystals which are placed on the top of the hive. As the menthol evaporates, it enters the trachea of the bees thus killing the mites.
An alternative treatment is a mixture of powdered sugar and Crisco. The bees go after the sugar and get covered with the Crisco. This interferes with the mite's ability to detect the young bees. As a result, the mite remains on the older bee and eventually dies with the bee. Be cautious with this treatment because it can attract hive beetles.
If you suspect Tracheal mites then you want to treat for the mites and then requeen.