16 superfamilies: 8 terrestrial and 8 aquatic.
Generally, larvae are ectoparasitic on arthropods, but certain groups feed on vertebrates (e.g., chiggers) and others are free-living. Post-larval stages (nymph and adult) are generally predators on other arthropods (esp. immobile stages such as eggs/pupae), but certain groups have evolved to subsist on other food sources (e.g., pollenivory in Balaustium).
Complete life cycle consisting of egg, prelarva, larva, nymphal stages (proto-, deuto-, and tritonymph), and adult.
Active stages include the parasitic larvae and free-living deutonymph and adult.
Inactive stages (calyptostases) include egg, prelarva, protonymph (nymphochrysalis), and tritonymph (imagochrysalis).
The red mites attached to arthropod hosts are almost always larvae belonging to this group. The ancestral life cycle of the parasitengones is to have a parasitic larva; regressive, inactive protonymph; active predatory deutonymph; regressive tritonymph; and active predatory adult. - Barry O'Connor