leaf-cutter, mortar, and resin bees

Megachile is a very large, very common and very widespread genus of bees known as leaf-cutter, mortar, and resin bees. It is cosmopolitan, occurring on every continent except Antarctica. It is most abundant and has the largest number of species in North America. There are 1,520 species in 56 subgenera worldwide, almost 140 species in 16 subgenera in North America, and at least 21 species in Minnesota. Seven non-native species have been introduced in the United States and some are now well established.

A few Megachile species are used commercially to pollinate agricultural crops. Alfalfa leafcutting bee was accidentally introduced sometime before 1940 and now is an important pollinator of alfalfa crops.

Female Megachile bees tend to cut pieces of leaves and carry them to their nests. This is the feature that gives the species its common name. The leaf piece is used as a cell separator.

Megachile bees have a stocky, gray or black, never metallic, often fairly hairy body with white stripes on the abdomen. Most are small, ¼″ to ⅜″ (7 to 9 mm) long.

On the first segment of the rear part of the body (T1) the transition from the forward-facing and upward-facing surfaces is abrupt, not gradual. On males, the rear of the abdomen turns down abruptly and is squared off, not gently tapered. On females, there is a brush-like tuft of pollen collecting hairs (scopa) on the underside of the abdomen. The claws at the end of each leg do not have a small pad (arolium) between them. Each claw has a small tooth near the base.

Sources

4, 24, 27, 29, 30, 82.

Bee (leaf cutter?) on common milkweed

Megachile spp. leaf cutter bee

Location: Fairview Twp, Cass Cty.

Bee (leaf cutter?) on common milkweed

Location: Barnes Prairie, Racine Co., WI

Location: Albany, NY

Location: Barnes Prairie, Racine Co., WI

Location: Slinger, Wisconsin

Location: Lake Shore, MN

There was a bee frenzy among my Golden Rod patch. So many different types of species, I couldn't count them.