The parasitic mite Acarapis woodi causes Acarine disease in honeybees by infesting the breathing tubes (tracheae) of the adult bee, piercing the trachea wall and feeding on the bee haemolymph.
Tracheal mites are invisible to the naked eye - they measure only 125 and 174 microns - and can therefore be seen only with a microscope. They are oval in shape and translucent-white in colour.[Fig 1]
Adult bees can be seen crawling on the ground or on grass in front of hives of heavily infested colonies. But this evidence may suggest more than a tracheal mite infestation - it may indicate the presence of other diseases.
To check for infection: adult bees are decapitated and the prothoracic collar removed with a scalpel. The thoracic tracheae can then be inspected. When stained, infested honeybee tracheae will show up as brown or black scabs or may be entirely black depending on the infestation level.[Fig 2]
Selective bee breeding is the first measure that beekeepers should employ to counteract tracheal mites. Buckfast bees, for example, are known to be highly resistant to this mite, while New Zealand strains are very susceptible.
Menthol crystals have been used with considerable success in North America although relatively high temperatures are required and the effects are variable.
Apiguard has been shown to work well in several countries in controlling tracheal mite numbers.