Megachile
Leafcutter and Resin Bees

In Minnesota, there are twenty-five described species within the genus Megachile. Two are not native to North America—Megachile rotundata (alfalfa leafcutter bee) that was introduced to pollinate alfalfa and Megachile sculpturalis (documented once in Carver county but not likely established in Minnesota). Collectively, Megachile are one of the most commonly observed genera in the family Megachilidae, especially in the summer months. All of the species that occur in Minnesota have solitary nests either aboveground in plant stems or cavities in wood, or belowground often under an object such as a flat stone. Depending on the species, the nest brood cells are partitioned and lined with whole leaf pieces, masticated leaves, petals, or plant resin. Bees in this genus can produce one or more generations per year.  

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Megachile are dark gray or black, small to large bees with a broad form. They have large mandibles, each with three to five teeth used to cut or gather supplemental nesting materials. Many species have hair bands on the rim of the abdominal segments (tergites). Bees in this genus lack an ariolum (pad between the tarsal claws), a common morphological trait of other genera in the family Megachilidae. Males have an abdomen that curves downward beginning at the sixth tergite. Also, many males have long hairs on their forelegs that they use to cover a female's eyes during mating. Megachile females collect pollen on hairs on the underside of their abdomen. Bees in this genus range in length from 5 to 21 mm (0.19 to 0.82 inches).