Diptera - Acroceridae

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About Diptera - Acroceridae

The family Acroceridae (Cyrtidae olim) is cosmopolitan, except for true oceanic islands, and contains 520 species in 3 subfamilies and 50 genera. Members of all 3 subfamilies occur in these regions, though most species have a quite limited distribution. The Philopotinae and Acrocerinae are represented here by only 1 genus each. In contrast, the most primitive subfamily, Panopinae, has 7 genera reported. Panops is recorded here only from Australia, however, Osten Sacken (1881a) lists an undetermined species from New Guinea. Endemicity in the family is 100% for species and 77% for genera in these areas. Altogether, 52 valid species in 10 genera and subgenera are listed.

All known species are internal parasitoids of true spiders (Araneae). They are either solitary or gregarious, with up to 14 larvae occurring per spider. Acrocerid eggs are tiny (microtype) and are usually deposited in high numbers (up to 5,000 per female). Eggs may be laid in flight (as in Eulonchus Gerstaecker), deposited on dead twigs (Ogcodes), on grass stems (Acrocera Meigen), or on tree trunks (some Pterodontia), but always away from the intended hosts. The 1st instar planidium actively seeks out and burrows inside the spider. There are 4 instars. The mature larva usually emerges posteriorly from the spider's epigastric furrow area. It pupates free from the host inside a protective webbing prepared by the spider before its death. The life span of the short lived, adult acrocerids ranges from 1 (commonly) to 6 (rarely) weeks. Mating occurs in flight or on dead twigs (Ogcodes) or at flowers (Eulonchus), usually from 1 to 2 days after emergence. Adults of Leucopsina, Mesophysa, Panops, and Helle are active nectar (flower) feeders. Adults of Ogcodes, Pterodontia, and Neopanops have small or mostly nonfunctional mouthparts and must be carefully looked for in meadows, forests, or other vegetated areas. Little is known about the biology and host relationships of acrocerid flies from these regions although Maskell (1888), Dumbleton (1941), and Plomley (1947a,b) figured and discussed several species of Ogcodes. Humphreys (1976) discussed parasitism by Pterodontia and Ogcodes. Schlinger (1987) reviewed the biology and host relationships of the Acroceridae of the world, including new records for these regions.