Say, T. (1823) Descriptions of dipterous insects of the United States. Journal of the Academy of Natural Sciences of Philadelphia 3: 9-32 [1823.04.??], 33-64 [1823.05.??], 73-104.
Epistrophella emarginata (Say)
Say (1823) described Scaeva emarginata from Florida. Dusek and Laska (1967) created a new genus for Syrphus euchromus Kowarz, 1885, Epistrophella and included emarginata. Vockeroth (1969) indicated the unusual variation in thoracic and abdominal markings of Epistrophe and suggested to use the two subgenera: Epistrophe s.s. and Epistrophella.
The analyses of larval morphology guided Rotheray and Gilbert to synonymize Epistrophella under Meligramma. Results from Mengual et al. (2008) suggested that Epistrophella is close to Xanthogramma, in agreement with larval evidence (Rotheray and Gilbert, 1999), close to the clade of Epistrophe but placed separately.
Xanthogramma divisa Williston, 1882: 311.
Syrphus disjunctus Williston, 1882: 314.
Xanthogramma fragila Fluke, 1922: 237.
Scaeva emarginata Say, 1823: 91.
Xanthogramma aenea Jones, 1907: 93.
Xanthogramma felix Osten Sacken, 1875: 49.
Syrphus infuscatus Fluke, 1931: 297.
Syrphus invigorus Curran, 1921: 171.
Syrphus weborgi Fluke, 1931: 299.
Syrphus disjectus Williston, 1887: 72.
Syrphus maculifrons Bigot, 1884: 89.
Epistrophella emarginata (Say)
Epistrophella species usually have dorsal and ventral pile patches of the katepisternum broadly separated and tergum 4th with a pair of narrowly or broadly separated yellow maculae.
Species very variable in coloration, as shown in the pictures of two males. Description adapted from Vockeroth (1992).
Head: Frons entirely yellow or narrowly to broadly black medially. Face and gena entirely yellow or lower margin of face and, more commonly, part of or entire gena blackish. Antenna varying from yellow-orange with upper margin darkened to mostly black.
Abdomen: Scutum with obscure dull yellow to well-defined bright yellow lateral vitta. Scutellar pili usually partly black, especially posteriorly, entirely yellow in some specimens; pleuron entirely dark or with obscure yellow pruinose areas on much of dorsal half. Wing with microtrichia very variable: at one extreme membrane nearly entirely trichose with only small bare area at base of cell c and near base of cell bm, at other extreme with cell c trichose only on apical one-sixth, cell R almost bare, cell bm with only very few microtrichia near apex, cell CuP bare on basal half or more, and bases of cells R2+3, dm, and CuA1 bare (with many intermediate conditions between these extremes). Legs almost entirely yellow with only coxae and metatarsus dark in some specimens, commonly with pale brown to dark brown ring on apical half or more of metafemur and with metatibia brownish towards apex, rarely with bases of all femora darkened.
Abdomen: Tergum 2 with pair of small yellow maculae widely separated from lateral margins in some specimens, or larger and commonly extending to margins, rarely narrowly confluent medially; tergum 3 with anterolateral corners or entire anterior margin narrowly yellow in some specimens, with pair of large yellow maculae commonly narrowly to broadly confluent medially, reaching lateral margins narrowly to broadly or extending forward anterolaterally to join anterolateral yellow maculae; some with narrow posterior margin yellow; tergum 4 similar to tergum 3 but large yellow maculae rarely confluent medially and broader posterior margin yellow; tergum 5 black with anterolateral corners yellow, or yellow with broad black inverted U or V. Sterna 2-4 entirely reddish yellow or some or all with obscure to distinct entire black fascia on posterior half, rarely almost entirely black.
Body length: 7.8-11.7 mm.
Larvae of E. emarginata have been reported feeding on several species of aphids (Aphididae) from different host plants (see Rojo et al. 2003), i.e. Aphis cornifoliae, Aphis gossypii, Chaitophorus populicola, Illinoia rubicola, Macrosiphoniella sanborni, Pterocomma smithiae, Rhopalosiphum cerasifoliae, Sitobion avenae, Uroleucon ambrosiae, and Uroleucon madia.
Nearctic species known from Manitoba to Quebec, south to Texas and Florida.