Epistrophe emarginata

Flower Fly
Epistrophe emarginata

Flower Fly Epistrophe emarginata male at Rondeau Provinical Park, May 07, 2006.
Flower Fly Epistrophe emarginata male at Rondeau Provinical Park, May 07, 2006.

Identification:
Head: Female face yellow with a black mark above antenna bases, may be divided. Male face yellow with brown-brassy spot above antenna base; eyes touching before simple eyes (ocelli) at top of head. Neither male or female have a dark stripe down middle below antenna bases. Hind eye margin curved, white hair.
Antenna: Blackish-brown on top half of entire length, lower half more reddish. Last joint large, oval, darker. Bristle (arista) long, dark.
Thorax: Metallic bronze-black, sometimes greenish. Segment 1 (scutum) sides have a yellow stripe on female; stripe is faint and more brownish-yellow on male. Both have long yellowish hairs along side edges. Segment 2 (scutellum or half-moon) yellowish-brown, outside edges sometimes dark, also with long yellowish hair. Thorax sides have a  large but obscure yellowish patch below wing base.
Wings: Wings lightly tinted with brownish-yellow, darker along outside edge (costa).
Legs: Yellow to reddish-yellow. Hind legs darker, sometimes with a darker ring on thigh (femur).
Abdomen: Black with large yellow marks and stripes which cover at least half the segment.
Segment 1: Very short, usually hidden by wings. Squarish yellow spot at base on each outside corner, touching side margin. Absent on female.
Segment 2: Stripe interrupted and somewhat pointed at centers. Not touching, but very close to side edges. White hair also along side edges. Stripe barely interrupted at center on female.
Segment 3: Stripe wider at side edges, but not touching side edges. Narrows to center and may be interrupted at center or continuous. Narrow yellow stripe along lower margin of segment, sometimes not visible on male.  On the female, the band is continuous.
Segment 4: Stripe wider at side edges, but not touching side edges. Narrows to center and always interrupted at center on male. On female stripe barely or not interrupted at center. Narrow yellow stripe along lower margin of segment.
Segment 5: Entirely yellow on female. On male reddish-yellow triangles at base of segment on each side; tip reddish-yellow.

Similar Species: Females are very similar to Eupeodes americanus males. Thorax has yellow borders and lower margin stripe on abdominal segment 3 is more obvious on Epistrophe emarginata females.

Size: 9 to 12 mm.

Habitat: Forest edges, farm fields, meadows.

Food: Adults feed on flower nectar. Larvae feed on aphids.

Flight Time: May to September

Life Cycle: Unknown, except that larvae eat aphids.

Comments: Essex County – Lake Erie Islands, Ojibway Prairies. Kent County – Rondeau Provincial Park per photos. Also in Michigan.

For information on synonyms, references and type specimens see next page

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