Tracheal Mite: Acarapis Woodi
Tracheal mites live in the honey bee's tracheae especially in the larger ones at the top of the thorax. It is believed that they are incidentally kept under control by the use of varroacides.

You can examine your bees by removing the head and chitinous collar of a bee and examine whether they are clear / white and healthy or brown if infested. You will need a low powered dissecting microscope or a jeweller's loupe to view the tracheae at about 30x magnification.

These mites feed by piercing the cuticle of the trachea and accessing haemolymph. Bees seem to be able to cope with an infestation of tracheal mites however the mites do shorten the life of the individual bee. This may cause the colony to die over winter

Download the Beebase pdf below for basic information and the extension document at the bottom for more detail.
Photo by Christine Coulson, Healthy trachaea
Scientific Beekeeping
Scientific Beekeeping
Courtesy The Animal and Plant Health Agency (APHA)
Diseased Right Trachea
Standard methods for tracheal mite research
Here is a photograph of a trachea infiltrated with tracheal mites. This was taken at a much higher magnification with a compound microscope. A mobile phone was held over the ocular lens to take the photo. The round artefacts are air bubbles.