Wasp-Mimic Flower Fly
Head: Face pale yellow. Black stripe down center continues above antenna bases on female. Male has small amount of yellow above antenna bases, eyes touching before simple eyes at top of head (ocelli). Eyes brown with cream spots and blotches. Mouth black.
Antenna: Black, long. Bristle (arista) yellow.
Thorax: Black. Segment 1 (scutum) with 4 yellow spots along base. A thin yellow line above wing bases, and an inverted V-shape on centre of lower margin. Segment 2 (scutellum) has a very thin yellow, curved line on lower margin. Thorax sides have a large oblong yellow spot, with a smaller spot below it. Sometimes a very tiny spot of yellow under wing base and near front leg.
Wings: Outer half dark, rest clear.
Veins reddish-brown. Halteres yellowish-white.
Legs: Thighs (femora) black to reddish, base yellow. Front shin (tibia) black, base and underside pale yellowish. Mid and hind shins yellow, tips reddish-brown. Front feet (tarsi) black, pale yellowish on underside. Mid and hind feet reddish-brown.
Abdomen: Black, somewhat shiny, long; about as wide as thorax. 4 yellow stripes. Segments 2 and 3 have small yellow dash on side edge between segments.
Segment 1 entirely black, short.
Segment 2 has large, raised stripe at base, sides thicker and continuing down segment to lower border.
Segment 3 stripe across mid segment, slight interrupt at centre.
Segment 4 stripe across mid segments, entire; another thin stripe along lower margin.
Underside black with 3 yellow, thin stripes.
Similar Species: Many species are similar to Spilomyia sayi like Ceriana abbreviata, Sphiximorpha willistoni and Temnostoma species. None have the colored marks in their eyes.
Size: 12 to 16 mm.
Habitat: Forest edges.
Food: Adults feed mostly on goldenrod.
Flight Time: Mid-August to mid-October.
Life Cycle: Larvae live in rotting wood, heartwood of deciduous trees.
Comments: Essex County per photos. Kent County – Rondeau Provincial Park. Widespread across Ontario. S. sayi mimics Mason Wasps Eumenidae.
For information on synonyms, references and type specimens see next page