Head: Dark green-blue, rough (deep punctures). Lower face (clypeus) flat, slightly darker. Sometimes with a very tiny white to cream-colored oblong mark, but usually no mark. No squarish mark on mouth area (labrum). Mandibles dark with 3 teeth.
Thorax: Dark green-blue. Segment 1 (scutum) rough (deep punctures) on base half, lower central area smooth and shiny. Thorax sides have black tubercle (pronotal lobe) with white fringe on one side. A few whitish hairs on lower half of thorax sides.
Wings: Wing knobs (tegulae) dark brown. Wings lightly tinted, veins brown.
Legs: Darker green-blue (slightly darker than body). Feet (tarsi) dark brownish-yellow. Front leg bare, mid and hind legs have long whitish hair. Hair on all feet slightly yellowish.
Abdomen: Dark green-blue. Tip sharply pointed. Some scant yellowish hair on last segment, and underside of last segment.
Head: Dark green-blue, rough (deep punctures). Lower face (clypeus) flat, slightly darker. White to cream-colored 3-cornered mark (hat-like). Another squarish, tiny white spot on mouth (labrum). Mandibles black with 2 teeth.
Antenna: Black. Segments 2 and 3 longer than wide.
Thorax: Dark green-blue, shiny and flat. Thorax sides have black tubercle (pronotal lobe) with crescent of white hair. Lower sides have sparse white hairs.
Wings: Wing knobs (tegulae) dark greenish-black. Wings tinted brownish, veins dark brown to black.
Legs: Darker green-blue than body, to almost black. Hind thighs (femora) have underside enlarged, V-shaped, no tuft of hair like C. strenua. Shins (tibiae) has sparse white hair, more so on hind shin. Feet more brownish, toes brownish-yellow.
Abdomen: Dark green-blue, rough (dense punctures). Segment 6 lower edge indented at center, with tuft of short pale hair. The 7th segment, usually hidden has a flat, wide tip (2 to 3 times as long as wide and fringed with whitish hairs. Underside covered with white hair.
Males are large and have V-shaped point on underside of hind thigh (femur). C. dupla males have no V-shaped point and males of C. strenua have obvious white stripe on front leg.
Size: Female 7 to 8 mm. Male 5 to 7 mm.; largest of the Ceratina
Habitat: Forest edges and meadows.
Food: Pollen and nectar from a wide variety of flowers.
Flight Time: Mid-March to mid-June; again late August to October.
Nest made by chewing out fresh twigs of elder, sumac, sassafras, blackberry, raspberry, roses, horseweed and teasel. Adults over-winter in the nests they were born in. Males start flying 2 weeks before the females, mating in April. The winter quarters (hibernacula) is not reused for new nests. Females stay with their young (6 or 7 only) until they become adults, thus living almost a year. Females sometimes produce one small female (usually the first to hatch) to help with the nest. Adults of new brood are seen by the first week of August. One generation per year.
Parasites: Chalcid Wasp Axima zabriskiei, Baryscapus americanus, Coelopencyrtus hylaeoleter, Eurytoma species.
Ichneumon Wasp Hoplocryptus zoesmairi, Eupelmus vesicularis, Grotea anguina.
Parasitic Wasp Gasteruption tarsatorius, Jewel Wasps Omalus iridescens and Parasierola species.
Blister Beetle Meloe angusticollis
Mite: Pyemotes ventricosus
Comments: Essex County – Point Pelee National Park. Kent County – Rondeau Provincial Park. Also Peel, Nipissing, Niagara and in Michigan.
For information on synonyms, references and type specimens see next page