Dianthidium simile

Leaf-cutter Bee
Dianthidium simile

Only one species occurs in Ontario. Black with white marks in Ontario. Farther south in U.S. the marks are yellow.

Identification:

Leaf-cutter Bee Dianthidium simile male on Stonecrop Sedum June 28, 2006 on Robinson Island, near Killarney, Ontario.
Leaf-cutter Bee Dianthidium simile male on Stonecrop Sedum June 28, 2006 on Robinson Island, near Killarney, Ontario.

Head: Dull black, rough; covered with very short pale hair. White mark behind each eye at top of head. Above mouth area (clypeus) white spot at each side, continues as a narrowing stripe up inner eye margins. Male has clypeus entirely white to pale yellow. Mandibles black on female, white on male; 3 teeth. Cheeks slightly narrower than eye width.
Note: Below the antenna bases, the antennal or sub-antennal sutures are usually curved, indented lines running down to clypeus, but on D. simile these lines are raised and jut outward – unique, but difficult to see.
Antenna: Black.
Thorax: Dull black, rough; very short white hairs. Collar (pronotum) widens considerably at each side edge; a white spot each side of center and another on tubercle on thorax side (pronotal lobe). Segment 1 has tiny points (axillae) at sides of lower margin, white and joined to stripe on segment 2. Segment 2 (scutellum) rounded at lower margin, with a wide white stripe following contours, and usually interrupted at centre. Thorax sides have long pale to whitish hairs under wing base.
Wings: Wing knobs (tegulae) reddish with a semi-circle of yellow to white on bottom edge. Wings darkly tinted, veins and marginal cell almost black.
Legs: Black with short, golden hair. Thighs (femora) have white at tips; less on male. Front and mid shins (tibiae) have large white streak. Hind shin has wide streak at base. Feet brownish-red on female; white streaks on male.
Abdomen: More shiny, black. Segment 1 has 3 squarish marks, two at side edges and one at centre. Segments 2 to 5 have curved white marks each side of center. Marks are thicker at each end. Segment 6 is entirely black. Segment 7 (male only) black base, rest white. Male abdomen tip white. Underside of female covered with golden hair (pollen basket). Underside of male somewhat reddish with long hair on 3 and 5.

Size: 8 to 10 mm. Male larger than female.

Habitat: Bare sand, with grasses; usually near streams, lakes or rivers and conifer trees.

Food: Nectar from a variety of flowers.

Flight Time: Late June to early September.

Life Cycle: Females dig their nests in sand, at the base of dried clumps of grass, forming a small cluster of cells with resin, small pebbles and sand. Nests usually face south and are hidden by dead grass leaves. Will nest communally (24 nests to 1 sq. meter (3 sq. feet). One report of a nest using rotting wood.

Comments: Northern Ontario; Sudbury, Muskoka, Parry Sound, Algonquin Park, Carleton County, Ottawa, Lanark, Victoria, Northumberland, Durham, Bruce, Georgian Bay (Go Home Bay BugGuide), Wellington (Guelph) and Norfolk.
Note: Two females collected at Port Hope, Ontario, July 28, 1895 (by W. H. Harrington, Nos. 52 and 53) reported by Swenk, 1914 – no records; not listed by Romankova 2003.

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

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