Spilomyia fusca

Wasp-Mimic Flower Fly
Spilomyia fusca

Wasp-mimic Flower Fly Spilomyia fusca female on Yarrow. July 13, 2007 Algonquin Provincial Park, Whitney, Ontario.
Wasp-mimic Flower Fly Spilomyia fusca female on Yarrow. July 13, 2007 Algonquin Provincial Park, Whitney, Ontario.

Identification:
Head: Head white. Black stripe above antenna base; another small mark below antenna base. Black outline around eyes, another stripe down middle of eye and a few dark spots on the white parts of eye. Male eyes touch each other in front of simple eyes (ocelli). Female has white continuing up to simple eyes.
Antenna: Black, 3rd joint slightly reddish-black. Bristle (arista) yellowish, as long as antenna.
Thorax: Black with white marks. Segment 1 (scutum) with two large white spots on each side at base. Wide white stripe on each side, curving to near centre. Two small white slanted stripes at center of segment end, forming a V-shape. Segment 2 (scutellum) black with a thin white line across end of segment. Thorax side has large oblong white mark, with a small spot below on each side of large mark. Another tiny white mark under wing base.

Wasp-mimic Flower Fly Spilomyia fusca female on Yarrow. July 13, 2007 Algonquin Provincial Park, Whitney, Ontario.
Wasp-mimic Flower Fly Spilomyia fusca female on Yarrow. July 13, 2007 Algonquin Provincial Park, Whitney, Ontario.

Wings: Wings slightly tinted, outer edge more reddish-brown. Veins reddish-brown. Halteres light brown.
Legs: Thighs (femora) base black, rest reddish-brown, hind thigh lighter with streaks. Front shin (tibia) black with a white base. Mid and hind shins white, tips slightly brownish-tan. Front foot black. Mid and hind feet brownish-tan.
Abdomen: Black, wide, oval.
Segments 1 and 2 entirely black. Segment 1 very short, hardly visible.
Segment 3 small white dash at each side edge; another white stripe along lower margin.
Segment 4 white stripe across middle of segment, interrupted at center; another stripe on lower margin, wider at center, looks almost V-shaped.
Segment 5 white, with some black at base on female; male tip may be all black.
Underside black, lower margin of each segment white.

Wasp-mimic Flower Fly Spilomyia fusca female on Ninebark. July 15, 2007 Algonquin Provincial Park, Whitney, Ontario.
Wasp-mimic Flower Fly Spilomyia fusca female on Ninebark. July 15, 2007 Algonquin Provincial Park, Whitney, Ontario.

Size: 16 to 17 mm

Habitat: Forest edges.

Food: Variety of flowers on trees and plants: basswood, elder, yarrow, ninebark, goldenrod

Flight Time: July to August

Life Cycle: Unknown.

Comments: Northern Ontario from north shore of Lake Superior to Algonquin Provincial Park to Thousand Islands. Mimic of the Bald-faced Hornet Dolichovespula maculata, and the two are often seen on the same flowering plants. Black front legs used to mimic Bald-faced Hornet’s antenna.

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

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