Toxomerus marginatus

Flower Fly
Toxomerus marginatus

Flower Fly Toxomerus marginatus female on Coreopsis. Jun 18-05 Wheatley, Ontario.
Flower Fly Toxomerus marginatus female on Coreopsis. Jun 18-05 Wheatley, Ontario.

Identification:
Head: Face yellow. Female has yellow stripe along inner eye margin, dark between stripes above antenna. Red eyes with hind margin indented and covered with yellowish hair.
Antenna: Yellow to reddish-yellow. Bristle (arista) long, black.
Thorax: Segment 1 (scutum) blackish-bronze with yellow stripe down each side and a yellowish pile stripe down the center. Segment 2 (scutellum or half-moon) can be yellow or sometimes partly covered with black pile. Thorax side dark with series of 3 yellow spots from wing base to front leg.

Flower Fly Toxomerus marginatus male on Fleabane. Stripes bleeding or joining together. Jun 21, 2007, Wheatley, Ontario.
Flower Fly Toxomerus marginatus male on Fleabane. Stripes bleeding or joining together. Jun 21, 2007, Wheatley, Ontario.

Wings: Clear, veins dark except for base and outer wing edge (costa) yellowish-orange. Halteres yellowish.
Legs: Pale yellow, dark stripe down hind shin (tibiae); feet brown.
Abdomen: Black with yellow to orange marks. Marks or pattern sometimes ‘bleed’ or coalescence.
Segment 1: Yellow to orange mark across center of segment, may be interrupted at center. Does not touch side edges.

Flower Fly Toxomerus marginatus female. Abdomen stripes orange May 07, 2007, Wheatley, Ontario.
Flower Fly Toxomerus marginatus female. Abdomen stripes orange May 07, 2007, Wheatley, Ontario.

Segments 2 and 3: Wide yellow to orange stripe, covers well over half the length of the segment, broken at center by a yellow-orange longitudinal line. Stripe does not touch side edges.
Segment 4: Yellow-orange oblong spot each side of center leaving a small dark stripe at center.
Tip black. Underside yellow to orange, the side edges usually visible from the top.

Flower Fly Toxomerus marginatus collecting on thistle. July 07, 2013. Wheatley, Ontario.
Flower Fly Toxomerus marginatus collecting on thistle. July 07, 2013. Wheatley, Ontario.

Similar Species: Toxomerus geminatus stripes on abdomen segments 2 and 3 are less than half the segment length, extend to side edges and are lobed.

Size: 5 to 6 mm.

Habitat: Meadows, forest edges, urban and farm areas

Food: Adults eat nectar and pollen from flowers.

Flower Fly Toxomerus marginatus female. Abdomen stripes bleeding or joining together. June 30, 2005, Wheatley, Ontario.
Flower Fly Toxomerus marginatus female. Abdomen stripes bleeding or joining together. June 30, 2005, Wheatley, Ontario.

Flight Time: May to October.

Life Cycle: Females lay eggs on plants with aphids. Larva consume the aphids and pupate in the soil. Many generations per year.

Comments: Essex County – Point Pelee National Park, Lake Erie Islands, Ojibway Prairies. Kent County – Rondeau Provincial park. Widespread in Ontario.

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

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