Alfalfa Leafcutter

• It is the most intensively managed solitary bee in the world: it transformed the lucerne seed industry in North America, tripling production.
• It cuts circular discs of leaf with its mandibles and lines each cell with them, hence the name leafcutter.
• It is solitary but gregarious: there is no queen and no division of labour, each female builds and provisions her own nest, but she prefers to do so alongside others. That is precisely what makes mass rearing possible, in straws or drilled wooden blocks.
• It arrived accidentally in the United States from Eurasia in the 1940s, and today it is on every continent except Antarctica.
• It only works on warm, sunny days, above 20 °C.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Grassland and lucerne crops; the female digs out or makes use of cavities — rotten wood, hollow stems, cracks — and lines them with cut discs of leaf

Sexual maturity

A solitary species: each female lays a single egg per cell and the adults emerge already mature at the end of summer

Gestation / incubation

The larva goes through four instars, consumes the pollen ball and enters diapause as a prepupa; pupation lasts 3 to 4 weeks and the adults emerge about 25 days later at 27 °C

Litter / clutch size

Between 30 and 40 eggs per female, one per cell

Sources consulted: https://es.wikipedia.org/wiki/Megachile_rotundata; Ficha de especie de Megachile rotundata; manuales de manejo del polinizador; bioRxiv 2022.01.09.475547

Best time: A single generation a year at high latitudes, emerging in late summer; in warmer climates some of the larvae skip diapause and give a second generation the same summer