Megachile

Leaf-cutter Bees
Megachile

 

Females are usually stout, dark-colored; hairy around the face. Most have a shovel-shaped or cone-shaped abdomen. A few have straight sides (parallel-sided). All the males are parallel-sided. Wings have only 2 nearly equal-sized sub-marginal cells, as in all Leaf-cutter Bees Megachilidae. Pollen basket or scopa on underside of abdomen is used to collect food for their young. Pollen is not collected on the hind legs like other female bees. The have wide mandibles with three or more teeth, and are long-tongued. Although females can sting, the seldom if ever do so, and are classed as stingless bees.

Size: 7 to 20 mm long.

Life Cycle: They nest in ready-made wooden cavities, in hollow plant stems, and in drilled wood nesting blocks (trap-nests) and at least one in pre-existing holes in soil. They do not excavate their own nesting holes. They cut nearly perfect arches out of leaves on roses and other plants which are used as nesting material. They can be rather particular about the leaves they use, returning repeatedly to the same plant. After constructing one cell, the bee adds nectar and pollen that has been collected on the underside of her abdomen. She lays one egg and plugs the cell with another cut leaf. There can be up to 20 cells per nest. The eggs hatch and eat the food provided. These white grubs stay in the ground for the rest of the summer, form a cocoon and emerge the following spring. Males emerge first. Females live only a few weeks – long enough to build and stock nests. A few Megachile use tree resin to build their nests.

Megachile species in Ontario: 14 species widespread across the province, except as indicated.

Females that have parallel-sided abdomens and mostly use resin for nesting material:
Megachile pugnata
M. campanulae – along Lake Erie & Ontario
M. sculpturalis – along Lake Erie & Ontario

Females that have cone-shaped or shovel-shaped abdomens and use leaves for nesting material:
Megachile addenda – south and central
M. centuncularis
M. frigida
M. gemula
M. latimanus
M. lippiae – south and central
M. melanophaea
M. mendica – along Lake Erie & Ontario
M. rotundata
M. texana
M. perihirta -north-west Ontario from Georgian Bay to Hudson Bay and west.