| | Insects of Britain and Ireland: the families of Diptera |
Adult insects. Antennae 3 segmented (third segment short); ‘modified’; aristate; the arista dorsal (pubescent or plumose). The second antennal segment not grooved. Ptilinal suture clearly defined. Post-vertical orbital bristles present; divergent. Mouthparts functional. The maxillary palps 1 segmented; porrect. Vibrissae present to absent (weak). Thorax without a continuous dorsal suture; without well defined posterior calli. Wing venation incomplete, in the sense of lacking one or more of the cells. Wings without a discal cell; without a sub-apical cell; without a closed anal cell. The costa unbroken (but attenuated both near the humeral cross-vein and at the junction of vein 1). Sub-costa apparent; joining vein 1 well short of the costa. Wing vein 4 extending far beyond the end of the first basal cell. Wings with the lower calypter much reduced or absent. Tibiae without a dorsal pre-apical bristle. Hind tibiae without strong bristles in the basal 4/5.
Larvae and pupae. The larvae acephalic. The pupae enclosed within a puparium.
Comments. Very small flies with variable, reduced wing venation.
Classification. Suborder Brachycera; Division Muscomorpha Schizophora Acalyptratae; Superfamily Opomyzoidea.
British representation. 7 species in Britain. Genera 3; Asteia, Astiosoma, Leiomyza.
Illustrations. • Asteia amoena (from Walker). Asteia amoena, with head in side view (2a), and detail of antenna (2b). From Walker (1853, Plate XVIII), with 2mm scale added.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the families of Diptera. Version: 14th April 2022. delta-intkey.com’.
