Largely undescribed order, with six families containing 42 species described, and over 150 species presumed to occur in Australia. Males possess enlarged, membranous hindwings, with little to no visible venation, and forewings reduced to long appendages. Males also have three pairs of legs and branched antennae. Females are wingless and often have no legs. Females are endoparasites of other insects, particularly beetles and wasps, clinging to their host with small mouthparts and typically remaining with host for their whole life; mouthparts of males reduced and non-functional.