British Insects: the Families of Diptera

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L. Watson and M. J. Dallwitz

Therevidae

Stiletto-flies, referring to the adult shape.

Life style non-parasitic.

Adult insects. Small to medium-sized; slender-bodied to robustly-built; stilt-legged to not stilt-legged. Antennae 3 segmented; ‘modified’ (basal segment long, second very short, third elongated-conical); with a non-annulated terminal segment; aristate to not aristate; the arista when present, apical (in the form of a short, sharp apical style). Ocelli present; 3. The top of the head with no marked depression between the eyes. Eyes asymmetric, nearly or quite connected above the antennae (males), or rounded, well separated (females). Mouthparts functional (proboscis short). The maxillary palps 1 segmented, or 2 segmented; porrect. Wings with a discal cell; without a sub-apical cell; with a closed anal cell. The anal cell relatively long. Wings with 8 cells between vein 3 and the anal cell. The costa extending around the entire wing. Sub-costa apparent; reaching the costa independently of vein 1. The leading edge veins not noticeably stronger than the rest. Wing vein 3 distally forked. Wing vein 6 present; reaching the wing margin. Wing vein 7 present; falling short of the wing margin. Wings with the lower calypter much reduced or absent; prettily patterned, or unpatterned. Feet without a triple pad. Said to be predatory (?).

Larvae and pupae. The larvae terrestrial (in sand or soil); predatory (on insect larvae, such as wireworms); hemicephalic. The pupae without a puparium.

Comments. Medium sized, elongated, densely bristly flies with slender legs. Ovipositor with a circlet of spines.

Classification. Suborder Brachycera; Division Asilomorpha; Superfamily Asiloidea.

British representation. 14 species in Britain. Genera 6; Acrosathe, Cliorismia, Dialineura, Pandivirilia, Spiriverpa, Thereva.

Illustrations. • Scenopinus niger: B. Ent. 609. • Scenopinus niger: B. Ent. 609, legend+text. • Scenopinus niger: B. Ent. 609, text cont.. • Thereva nobilitata (from Walker). • Thereva nobilitata (Verrall 1909).


To view the illustrations with detailed captions, go to the interactive key. This also offers 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.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: the families of Diptera. Version: 1st January 2012. http://delta-intkey.com’.

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