Megachile pugnata

 

Sunflower Leafcutter
Megachile pugnata

 

Identification:
Female:

Leaf-cutter Bee Megachile pugnata female on Cup Plant. Aug 12, 2008, Wheatley, Ontario.
Leaf-cutter Bee Megachile pugnata female on Cup Plant. Aug 12, 2008, Wheatley, Ontario.

Head: Black, large and square with a wide area of thick, yellowish-white hair surrounding antenna bases, reaching to inner eye margin. Top of head dull, with a few black hairs. Area above mouth (clypeus) extremely short. Cheeks twice as wide as eye width with a projection extending downward at lower back edge of cheek and yellowish hair on underside. Mandibles black, extremely large, wide and long; curved and fringed on underside with golden hair.
Antenna: Black.
Thorax: Black, bald to sparse black hairs on top of thorax. Yellowish-white hair along base or collar area. Yellowish-white mixed with mostly black hair on lower edge of thorax, with a fringe of yellowish hairs along sides from wing bases to end. Thorax sides covered with dense, yellowish-white hair.
Wings: Wing knobs (tegulae) black. Wing tinted a dark brownish-yellow, tips darker. Veins brown-black.

Leaf-cutter Bee Megachile pugnata female flying to Cup Plant. Aug 11, 2008, Wheatley, Ontario.
Leaf-cutter Bee Megachile pugnata female flying to Cup Plant. Aug 11, 2008, Wheatley, Ontario.

Legs: Brownish-back with whitish-yellow fringe on underside of all thighs (femora). Shins (tibiae) have very short bright orange-yellowish to golden hairs and short fringe on underside. Feet reddish-brown with darker orange-yellowish to golden hairs, more orange-yellow on underside.
Abdomen: Black, parallel-sided, not cone-shaped as most Megachile.
Segment 1: Dense whitish-yellow hair at side edges; darker, shorter hair at center. No hair band.
Segments 2 to 5: Entire (uninterrupted) dense yellowish-white hair bands on the lower edge. Segments 2 to 4 have an indented line or groove near base; no white pile.
Segment 6: No marks, tip is small, rounded with a very slight up-curved lip.
Underside: Covered with yellowish-white to yellow hair (pollen basket). Segment 6 at tip has very short yellow hair with only a few black intermixed.

Leaf-cutter Bee Megachile pugnata male on Cup Plant. Aug 12, 2008, Wheatley, Ontario.
Leaf-cutter Bee Megachile pugnata male on Cup Plant. Aug 12, 2008, Wheatley, Ontario.

Male:
Head: Black, large, square; thick long yellowish-white hair covering face. Top of head scant black hairs with a few white, but mostly bald, surface dull. Cheeks equal to eye width, with a thick fringe of white hair at back edge. Mandibles small, short with a short spine on underside, hidden by white hair.
Antenna: Black. Tips very slightly longer and wider.
Thorax: Black, bald, surrounded with a slight fringe of whitish hair. Thorax sides more gray-white with some white tufts.
Wings: Wing knobs (tegulae) brownish-yellow. Wings tinted brownish-yellow, tips darker. Veins reddish-brown to black.
Legs: Black with yellowish-white fringe on underside of all thighs (femora). All shins lightly covered with yellowish hairs. Feet reddish-brown, mid foot (basitarsi) has dense short, yellowish-white hair.

Leaf-cutter Bee Megachile pugnata male close-up of unusual front leg. Aug 12, 2008, Wheatley, Ontario.
Leaf-cutter Bee Megachile pugnata male close-up of unusual front leg. Aug 12, 2008, Wheatley, Ontario.

Main ID: Front foot segment 1 (basitarsi) very large. Expanded front area has whitish-yellow hair with orange tip; very long fringe of orange-yellow, hair tips darker, on underside.
Abdomen: Black, parallel-sided
Segment 1: Base straight across, not rounded. Segment covered with long pale hair. Hair band on lower margin at side edges only.
Segments 2 to 4: Indented or grooved lines at base of segments, with white pile; sometimes not visible on 3 if segment is retracted, usually visible on segment 4. Lower margin has white hair bands, not interrupted at centre: narrow on 2; wider on 3 and 4.
Segment 5: Slightly curved under with sparse, narrow white hair band on lower margin.
Segment 6: Curved under. Tip has several small projections (not spines) each side of indented or notched centre.
Underside: Rows of yellowish-white hair tufts, almost as long as female’s pollen basket.

Size: Female 15 to 17 mm. Considered large. Male 11 to 13 mm.

Habitat: Forest edges and meadows.

Food: Said to prefer Sunflowers Helianthus, but the majority of bees can be found on Cup Plant Silphium perfoliatium even when Helianthus is available.

Flight Time: July and August

Life Cycle: Nests in borings of dead sumac twigs, trap-nests, rotting logs. Usually, Megachile females that use resin all have parallel-sided abdomens, not cone-shaped like the rest of the Megachile. M. pugnata also has a parallel-sided abdomen, but does not use resin, instead chews parts of leaves, mixing them with soil particles (not mud) and secretions from the abdomen tip for ‘glue’. Then, smooths the cell walls with her head. Egg to adult 36 to 37 days. One generation per year in Ontario, possibly two in Michigan (June to September).

Parasite: Leaf-cutter Cuckoo Bee Coelioxys alternata.

Comments: Essex County – Point Pelee, Ojibway Prairies. Kent County – Rondeau Provincial Park. Widespread in Ontario and southern Michigan.

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

Leave a Reply