in morphology and ethology. The taxonomic history of the Therevidae accordingly has undergone repeated revisions; in the past, many therevids were assigned to other families, and many other Brachycera were assigned to the Therevidae. Since the 1970s however, there has been a great deal of rationalisation of the taxonomy, particularly by Lyneborg and Irwin. Revision of the higher taxa, based on the phylogenetic cladistic relationships between various groups of Asiloidea has led to a better understanding of their ranks and interrelationships. Originally the Therevidae sensu lato, were polyphyletic. It required the reassignment of some subfamilies to other families, together with adjustments to closely related families in the Asiloidea, to establish consistent phylogenetic relationships. The Therevidae now constitute a monophyletic clade that English-speaking dipterologists call the therevoid clade (clade of "Terevoidi"). This group has not been assigned a ranking at any taxonomic level above the rank of family, but for the present is recognised as a group of families within the superfamily Asiloidea. Therevoid clade Clade showing relationship of Asiloidea At present, over 1, 600 species are known. After taxonomic revisions by Lyneborg (1976) and Winterston et al. (2001), the family is divided into four subfamilies, among which the most representative in size and diffusion is the Therevinae: Agapophytinae: 12 genera Phycinae: 13 genera Therevinae: 84 genera Xestomyzinae: 12 genera In addition to the 121 living genera are several extinct genera known from Cenozoic deposits including Dasystethos, Glaesorthactia, Kroeberiella, and Palaeopherocera, in doubt is Helicorhaphe. The oldest known member of the family is Cretothereva from the Early Cretaceous (Aptian) Crato Formation of Brazil. Habitat and distribution The habitat of the Therevidae is more varied than that of other Asiloidea, but as in Asiloidea, preferred ecosystems better suit the larvae, so these insects are more common in thickets of xerophilous plants (garrigue and maquis, in deserts and on sandy beaches. The Therevidae are represented in all zoogeographical regions of the Earth. The Therevinae are present in all continents, with a lower frequency in the eastern region . The Phycinae have spread to the Afrotropical and the Holarctic. The Xestomyzinae are mainly Afrotropical. The Agapophytinae are endemic to the Australasian realm. In Europe, only the subfamilies are represented:- Phycinae, with two genera, and Therevinae, with 15 genera. A total of 98 species are reported, two-thirds of which belong to the genus Thereva. Species lists Palaearctic Nearctic Australasian/Oceanian Japan World list List of soldierflies