Leafcutter bees are solitary bees, native to woodland areas. There are more then 140 species found in North America. These grayish coloured bees use their mouthpieces to cut pieces out of leaves to line their nests. Sometime they are very particular about which plant leaves they use. The nests are made in wood cavities already present or in hollow plant stems.
Leafcutters are very efficient pollinators. They prefer legume blossoms, but are by no means limited to one plant’s nectar.
The alfalfa leafcutter bees (Megachile rotundata) got their name by pollinating alfalfa, and are distinct because they have pollen baskets that are on their abdomens, rather than on their hind legs, like honeybees. They are black with pale yellow strips on the abdomen and face.
In Canada these bees are famous for saving the Canadian alfalfa seed industry. In the first half of the twentieth century alfalfa seed production decreased because expanding agriculture and land clearing destroyed nesting sites of native bees. By 1950 Canada was importing alfalfa seed to meet 95% of its domestic needs. The new leafcutter bee was introduced to Canada in 1961, and it pollinated alfalfa better than any other insect.
Honeybees, one of the best pollinators, are ineffective alfalfa pollinators because they can steal nectar without tripping the flower. The leafcutter bee not only does the pollination job well, but is much gentler and less likely to wander away while pollinating than honeybees. Besides their contribution to pollination, leafcutter bees have created a new kind of beekeeper: one who sells bee larvae to other growers in need of pollination services.