What Bug Is That? The guide to Australian insect families.

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Mydidae

Overview

A small family of handsome flies, of moderate to very large size (the South American Mydas heros is one of the world's largest flies). Yeates and Irwin (1996) moved the Megascelinae, containing the Australian genus, Neorhaphiomydas , from the Apioceridae to the Mydidae. This genus has close relatives in Chile, South America, and western North America. Paramonov (1950) revised the fauna, and added new species in subsequent publications over the following decade. The Australian fauna currently consists of around 40 described species in four genera, the two largest genera being Diochlistus and Miltinus .

Mydids are not very common, but occupy a wide variety of habitats, usually in open country. Miltinus viduatus is widespread, found both in the humid eastern regions and the dry interior, but most species seem to be much more restricted in range and habitat. Adults may be taken visiting flowers such as Leptospermum , but it is thought that at least some are predators. The larvae are similar in appearance to Asilidae larvae, and are said to be predacious. They are recorded in other countries as feeding on beetle larvae in rotting wood; they have been little studied in Australia. Norris (1938) described the eggs and first two instars of Anomalomydas mackerrasi from Western Australia.

Description

Most mydids bear a superficial resemblance to Asilidae and Apioceridae, all except Neorhaphiomydas are recognisable by the long, clubbed antennae, and all have complex venation of closed cells and recurved wing veins. Many are wasp mimics, and example being Diochlistus auripennis , which resembles the large, orange-winged Pompilidae.

Distribution

The Australian fauna has a striking distribution, resembling that of the Apioceridae. There are four genera, all endemic: Neorhaphiomydas lacks an elongate and club-like antennal flagellum; Anomalomydas with cell cup widely open; Diochlistus with M2 present; and Miltinus with M2 absent. Diochlistus is found in most States, but is best represented in southern Queensland - by six of the 12 known species. Miltinus , however, is found mainly in the more arid areas, occurring around, and presumably in, the desert interior. There are seven species of Neorhaphiomydas , all of which are associated with sandy soils in Western Australia and South Australia. The two species of Anomalomydas are known only from South Australia and Western Australia. The world fauna generally seems to be an old one, adapted to hot and/or arid climates, and has probably suffered much extinction due to climatic changes.

  • Miltinus stenogaster

  • Miltinus maculipennis, Wasp-mimicking mydas fly

  • Mydas sp.

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