A leafcutting bee, Megachile sp. (Hymenoptera: Megachilidae), adult. Photo by Drees.
Common Name: Leafcutting bee
Scientific Name: Megachile sp.
Order: Hymenoptera
Description: Adults resemble honey bees. They are mostly black with light bands across the abdomen and a covering of pale hairs on the underside. Females carry pollen on stiff yellow hairs on the underside of the abdomen rather than on the sides of the hind legs like honey bees. Leafcutting bees can be distinguished from other bees by their wing venation (they have two submarginal cells of equal length).
Not all species of Megachilidae construct nest cells with pieces of leaves. Carpenter bees also construct cells in holes they dig in structural beams or branches. However, carpenter bees do not construct their cells from pieces of leaves.
Life Cycle: They are solitary nesters. Females stack cylindrical, blunt-ended leaf-lined cells in deep nesting holes. One egg is laid in each cell. A white, legless, grub-like larvae hatches from the egg and develops through several stages (instars) before pupating within the cell. Cells are stacked end-to-end. Some species of leafcutting bees are parasitic.
Habitat, Food Source(s), Damage: Larvae have chewing mouthparts and adults have more complex mouthparts. Adult females cut circular or elongate pieces from leaves, particularly from rose, but also from azalea, ash, bougainvillea, redbud, and other cultivated and wild plants. Uses leaf pieces to construct walls and partitions of nesting cells in which young develop. Nests are located in hollow twigs, other natural cavities, holes in buildings and occasionally in the ground. Cells are provisioned by adults with nectar and pollen collected from flowers. Artificial nesting sites can be made by drilling holes of the appropriate size in boards, or by using bundles of large soda straws.
Pest Status: These bees cut nearly circular pieces of leaves of roses and other plants for nesting material. Nests made in walls of buildings can be a nuisance and cause ninor structural damage. They are important pollinators of plants. The alfalfa leafcutting bee, Megachile rotundata (Fabricius), is an important pollinator of alfalfa, and can be encouraged to nest in man-made structures. Females are capable of stinging.
For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices.
Literature: Borror et al. 1989; Johnson & Lyon 1988; Werner & Olson 1994.