Megachile

Megachile is a genus of bees in the family Megachilidae, within the order Hymenoptera. Members are commonly known as leafcutter bees, a name that reflects their distinctive nesting behavior. The genus comprises hundreds of species with a wide geographic distribution, many adapted to temperate regions but occurring globally.

Most Megachile species are solitary. Females construct and provision their own nests, rather than forming colonies. A characteristic feature is the method of pollen transport: females carry pollen on specialized hairs on the ventral abdomen (the scopa) rather than on the hind legs as in many other bees. Adult size and coloration vary by species, with bodies often dark and some species showing bands, hair patterns, or metallic sheen.

Nesting behavior centers on using leaf pieces to form brood cells. Females cut neat circular or oval fragments from leaves or petals and assemble them into nest cells within natural cavities such as hollow stems, dead wood, or crevices, and occasionally in artificial substrates. Each brood cell is provisioned with a mixture of nectar and pollen, an egg is laid on the store, and the cell is sealed. The larva develops inside the cell and overwinters as a pupa, emerging as an adult in the following season.

Ecology and significance: Megachile species are important pollinators for a range of flowering plants, including crops. Some species, notably Megachile rotundata (alfalfa leafcutter bee), are used commercially to improve pollination. Because they are solitary and nest-site dependent, they can be sensitive to habitat loss and pesticide exposure. Conservation efforts focus on preserving nesting habitats and providing cavities or bee hotels to support populations.