Leafcutter Bee

Megachile rotundata (Fabricius), the alfalfa leafcutter bee (family Megachilidae), is a solitary bee, usually 6-10 mm in length, with a robust, dark body sparsely covered with pale hairs. Like other Megachilidae, females possess a scopa on the underside of the abdomen used for collecting and carrying pollen. They are non-aggressive and rarely sting. Females construct linear nests in pre-existing cavities, lining and dividing individual cells with neatly cut pieces of leaves, typically circular or oval sections. Each cell contains a pollen-nectar provision and a single egg. Multiple generations can occur in warmer regions.

Leafcutter bees are important pollinators, particularly of alfalfa and other legumes. Females use their mandibles to cut distinctive circular or oval pieces from leaves, which they then transport to their nesting sites. These leaf pieces are meticulously used to construct and line individual brood cells within the pre-existing tunnels. They are solitary bees, meaning each female independently builds and provisions her nest without social cooperation. Adult activity begins in late spring and continues through summer.