Allograpta obliqua

Oblique Flower Fly
Allograpta obliqua

Identification:

Flower Fly Allograpta obliqua female on Iris. May 16, 2010, Wheatley, Ontario.
Flower Fly Allograpta obliqua female on Iris. May 16, 2010, Wheatley, Ontario.

Head: Face entirely yellow on male, pointed at top where red eyes join. Female has yellow stripe up inner eye margin, rest brown; eyes separated at top. Face does not protrude in either male or female. Hind eye margin indented near middle, covered with white hair.
Antenna: Female antenna dark. Male antenna light yellowish-brown.

Flower Fly Allograpta obliqua male on Jerusalem Artichoke. Sep 12, 2007. Wheatley, Ontario.
Flower Fly Allograpta obliqua male on Jerusalem Artichoke. Sep 12, 2007. Wheatley, Ontario.

Thorax: Segment 1 (scutum) metallic bronze to greenish – no longitudinal lines.  Wide yellow stripe on side edges, broken at wing base. Segment 2 (scutellum or half-moon) yellow, sometimes tinted with obscure reddish brown. Thorax sides black with many oblong yellow spots covering surface.

 

 

Flower Fly Allograpta obliqua female on Goldenrod, Oct 13, 2011, Wheatley, Ontario.
Flower Fly Allograpta obliqua female on Goldenrod, Oct 13, 2011, Wheatley, Ontario.

Wings: Clear, veins black. Halteres yellow.
Legs: Front and mid legs yellow. Hind legs dark, mixed with some yellow rings. Feet dark. Toes yellow.
Abdomen: Black with yellow to yellow-orange marks.
Segment 1: Very short, mostly at each side of scutellum. Base has wide yellow stripe bending around scutellum. Lower margin black.

Flower Fly Allograpta obliqua male on Meadow Parsnip. Jun 28, 2004. Wheatley, Ontario.
Flower Fly Allograpta obliqua male on Meadow Parsnip. Jun 28, 2004. Wheatley, Ontario.

Segment 2: Thin yellow stripe at base, broken at center. Another wider yellow stripe across middle of segment.
Segment 3: Thin yellow stripe at base, slightly broken at center. Another very wide yellow stripe across middle of segment, somewhat curved on female; much wider and more curved on male.
Segment 4: Thin yellow stripe entire across base, with 2 longitudinal lines down middle of segment. Another long, oblong mark on each side. Main ID.
Segment 5: Thin yellow stripe entire across base, with four longitudinal, wider lines extending to lower margin. Lower margin yellow.
Tip rounded, dark. Underside yellow.

Similar Species:  Toxomerus species do not have longitudinal lines on the abdomen.

Size: 5 to 9 mm long.

Habitat: Meadows, forest edges, urban areas with aphids.

Food: Adults feed only on pollen, nectar, or honeydew produced by aphids, particularly fond of mint. Larvae feed on aphids and plant lice or mealybugs.

Flight Time: April to September.

Life Cycle: Can have 4 to 7 generations a year, with a complete life cycle in as little as 16 days. Eggs are chalky-white, laid on leaves and stems infested with aphids or plant lice. Larvae hatch in 3 to 4 days, maggot-like, mouth with teeth. Brown to green with white areas, about 8 to 9 mm long when mature. They can devour 400 aphids during larva stage. Larvae need some shade. They protect themselves from predators, like ants, by a secretion from their mouth, a glue-like substance that immobilizes the predator.
Parasitized by tiny Ichneumonidae wasps.

Comments: Essex County – Point Pelee National Park, Ojibway Prairies. Kent County – Rondeau Provincial Park. Georgian Bay area to Toronto.

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

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