ENDOPARASITISM has hitherto been considered exceptional among the trombiculid mites and confined to the two genera Hannemania and Endotrombicula, the larvae of which bury themselves in the skin of amphibians. Recent discoveries have, however, shown that endoparasitism is much more widespread among the Trombiculidae than has been suspected. Some of the endoparasitic forms are indeed very common but have been overlooked. Two distinct habits are recognized: burrowing in the skin, and living in the nasal cavities.