Stelis louisae

Cuckoo Leaf-cutter Bee Stelis louisae female on Ox-eye Sunflower. Aug 15, 2016 Leamington, Ontario.
Cuckoo Leaf-cutter Bee Stelis louisae female on Ox-eye Sunflower. Aug 15, 2016 Leamington, Ontario.

Cuckoo Leaf-cutter Bee
Stelis louisae

Identification:
Head: Black with a few white hairs from antenna base to top of head. Wide yellow stripe up inner eye margin. Top of head (vertex) has yellow stripe which may be interrupted at center across back of head (see note). Simple eyes (ocelli) large. Mandibles black with 3 teeth. Cheeks slightly narrower than eye width. Male has yellow wavy stripe above mouth area (clypeus).

Cuckoo Leaf-cutter Bee Stelis louisae on Oregano. July 31, 2013 Wheatley, Ontario.
Cuckoo Leaf-cutter Bee Stelis louisae on Oregano. July 31, 2013 Wheatley, Ontario.

Antenna: Black.
Thorax: Black with yellow stripes. Collar yellow, continues around side edges to wing knobs (tegulae), widely interrupted at center. Segment 2 (scutellum) has two very small projections (axillae) at each side, yellow. Yellow continues around lower edge of segment 2. Thorax side has yellow tubercle with raised edge. Large yellow spot below tubercle; smaller spot behind wing base. (see note).
Wings: Wing knobs (tegulae) large, yellowish-brown. Wings lightly tinged, darker in marginal and sub-marginal cells. Veins brownish.
Legs: Thighs (femora) black with brownish-yellow tips; sometimes almost ½ black. Shins and feet brownish-yellow.

Cuckoo Leaf-cutter Bee Stelis louisae female on Ox-eye Sunflower. Aug 15, 2016 Leamington, Ontario.
Cuckoo Leaf-cutter Bee Stelis louisae female on Ox-eye Sunflower. Aug 15, 2016 Leamington, Ontario.

Abdomen: Black with yellow marks.
Segment 1 has a wide band across segment, may be slightly reddish on lower edge.
Segment 2 has long oval spot at each side edge. (see note)
Segments 3 and 4 stripes have notches (emarginate) on base edge of stripe, may be entire, or interrupted.
Segment 5 has a short stripe more in center, unbroken.
Segment 6 entirely black, not spined.

Cuckoo Leaf-cutter Bee Stelis louisae male on Cup Plant. Aug 13, 2009 Wheatley, Ontario.
Cuckoo Leaf-cutter Bee Stelis louisae male on Cup Plant. Aug 13, 2009 Wheatley, Ontario.

Male: Segment 7 entirely black; underside of segment 2 is large and partly covers segment 3. Segment 4 to 8 mostly hidden. Underside of abdomen tip has pair of thick spines at center, and a tuft of long hairs at each side edge. Female underside black.

Note: Marks at back of head and on the side of the thorax are usually missing in Ontario (Essex County considered the northern limit of the species) and an additional dashed line may be present at centre of abdomen segment 2 (references Johnson, 1979). Further south the yellow marks and legs are more orange. Because the male abdomen curls under, male and female are difficult to tell apart, except for the partly yellow clypeus on the male.

Size: 8 mm.

Cuckoo Leaf-cutter Bee Stelis louisae on Oregano. July 31, 2013 Wheatley, Ontario.
Cuckoo Leaf-cutter Bee Stelis louisae on Oregano. July 31, 2013 Wheatley, Ontario.

Habitat: Meadows and forest edges.

Food: Adults feed on nectar from flowers. Larva are parasites of other Leaf-cutter bees.

Flight Time: Mid-July to August

Life Cycle: Parasitizes Leaf-cutter Bee Megachile campanulae.

Comments: Apparently only found in Essex County – Point Pelee, Ojibway Prairies. Considered the northern extent of the species.

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

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