Stelis coarctatus

Cuckoo Leaf-cutter Bee
Stelis coarctatus

 

 

Cuckoo Leaf-cutter Bee Stelis coarctatus on Ox-eye Daisy. May 29, 2009, Wheatley, Ontario.
Cuckoo Leaf-cutter Bee Stelis coarctatus on Ox-eye Daisy. May 29, 2009, Wheatley, Ontario.

Identification: Male and female almost identical.
Head: Black with some long white hairs around antenna bases; no other marks. Mandibles with 3 teeth. Cheeks slightly wider than eye width with a few short, white hairs. Male has lower face (clypeus) slightly protruding and more hair on face.
Antenna: Black, 10 segments on female, 11 on male. Pedicel longer than segment 1. 1st segment constricted at base.
Thorax: Entirely black, rough. Thorax sides have some long white hair. Tubercle (pronotal lobe) slightly raised, entirely dark. Male has more hair on thorax top and sides.
Wings: Wing knobs (tegulae) large, dark and projecting outward. Wings smoky tinted, darker toward tips. Veins black.
Legs: Black, with dusting of very short white hair. Shins (tibiae) pointed at tips.

Cuckoo Leaf-cutter Bee Stelis coarctatus on Ox-eye Daisy. May 30, 2009, Wheatley, Ontario.
Cuckoo Leaf-cutter Bee Stelis coarctatus on Ox-eye Daisy. May 30, 2009, Wheatley, Ontario.

Abdomen: Black, slightly shiny. Segment 1 to 3 have a very small white to cream spot at each side edge. Segment 4 has a very tiny dash each side of center, sometimes absent on male. Abdomen tip rounded, grooved and slanted down on female. Underside of male hairy.

Size: Female 6 to 7 mm. Male 5 mm.

Habitat: Meadows and forest edges.

Food: Adults feed on flower nectar.

Flight Time: May to early July

Life Cycle: One generation per year, over-winters in a prepupal stage in the nest of its host, the Leaf-cutter Bee Hoplitis carinata.

Comments: Not on any lists for Ontario. Wheatley per photos. Found in New Brunswick in 2001. Canadian National Collections (CNC) lists 8 (7 S. coarctatus & 1 S. vernalis), no locations. Also in southern Michigan.

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