Identification: Abdominal segment 5 on female turns downward or is depressed. Unique.
Head: Reddish-brown, with black between antenna bases and simple eyes (ocelli). Hair on the sides of the top of head rather dark and erect, otherwise very thin, short and white. Cheeks nearly as wide as eyes, hind margin black. Mandibles slender and toothless.
Antenna: Base (scape) entirely reddish-brown. Segments reddish-brown on base half, rest somewhat lighter. Underside reddish-yellow.
Thorax: Reddish-brown. Collar yellow; ends black. Segment 1 has black mid line. Segment 2 middle quite deeply impressed; slightly reddish. Segment 3 (propodeum) mostly red with black side margins; or black with yellow side margins. Sides have wide blackish lines. Tubercle (pronotal lobe) yellow, small spot near tubercle yellow. Underside reddish-brown, slightly hairy.
Wings: Wing knobs shiny, reddish-brown. Wings faintly yellowish.
Legs: Reddish-yellow. Thighs (femora) more or less black at base and on underside.
Abdomen: Segments mostly rusty reddish-brown with blackish lower margins.
Segment 1 with the base black, rest reddish.
Segment 2 with large yellow stripe, pointed inward, interrupted at centre.
Segment 3 has smaller yellow oblong stripe, wide interrupt at centre.
Segment 4 with a pair of much smaller, lighter yellow marks inset from edges; sometimes no marks.
Segment 5 has a short yellow semi-divided patch or sometimes just a line with a slight break at centre, lower part of segment angled downward and ‘depressed’ with silvery-white line at bottom. Tip squared.
Head: Dark reddish-brown with black from mouth to top of head. Rusty reddish-brown, narrow marks surround top of eye and extend down the back of the eye. Front lower eye margin (from antenna bases downward) is yellow. Cheeks slightly narrower than eyes, hind margin dark. Mandibles toothless, yellow, tips dark. White, thin hair on lower face.
Antenna: Base (scape) strongly swollen, yellow on underside, becoming darkened on top side. Segments are brownish-black on base half, upper half lighter on top side. Underside brownish-yellow. Segment 1 shorter than 2.
Thorax: Dark reddish-brown. Collar yellow. Segment 1 (scutum) with very deeply grooved, wide black mid line, sometimes absent. Segment 2 (scutellum) deeply divided, often more reddish. Segment 3 (propodeum) black but with a faint, reddish area on each side margin, white hair. Thorax sides largely red but with a small yellow spot near wing base and a narrow transverse line of black just below wing bases. Tubercles (pronotal lobes) yellowish-brown. White, thin hairs on lower thorax sides. Underside is black.
Wings: Wing knobs reddish to yellowish. Wings faintly yellowish.
Legs: Legs mostly brownish-yellow to reddish, tips lighter; hind thigh darker. Thighs (femora) blackish on underside.
Abdomen: Dark red-brown, but slightly paler than thorax.
Segment 1 base ½ black, lower ½ reddish with some yellowish along centre, or lateral spot each side.
Segment 2 has very wide yellow spot, pointed at centre, narrowly interrupted, margin red.
Segment 3 yellow stripe, covers 1/3 of segment on each side, rest of stripe area reddish.
Segments 4 to 6 have incomplete yellow bands always interrupted at centre, except 6; all stripes may be missing on 4 to 6. White hairs on side edges.
Tip dark red, deeply lobed.
Underside of 2 and 3 largely yellow, margins darker.
Size: Female 6 to 12 mm. Male 8 mm
Habitat: Forest edges and meadows.
Food: Pollen and nectar from flowers.
Flight Time: June
Life Cycle: Parasitic on Mining Bees Andrena species.
Comments: Essex County – photos. Niagara (St. Catharines) and Michigan.
For information on synonyms, references and type specimens see next page