Note:  Do not rely on this information. It is very old.

Tracheal Gills

Tracheal Gills are the structures. found in many aquatic insects by which respiration is effected. They resemble and act as gills, though morphologically they are tracheae. These are minute tubes usually ramifying throughout the whole body of the insect. In the aquatic forms these extend out from the body as plates or tufts, which come in contact with the air dissolved in the water.