Leafcutting bees

In spring or summer, depending on the species, leafcutting bees leave their individual cells where they have spent the winter. The males usually come out first, and mating occurs as soon as the females emerge.

Female leafcutting bees build their own nests and stock them with food. They may make a nest in various kinds of cavities or underground. Nests consist of a series of cells laid end to end. Each thimble-shaped cell is made of bits of leaves or petals cut up by the bee with its mandibles. Once a cell is ready, the bee stocks it with pollen and nectar. Then it lays an egg on this food supply.

After laying, the bee seals the cell, generally using bits of leaves or petals. Once the nest is full, the bee blocks off its entrance. A female may build more than one nest. Larvae are white when they hatch. Each one has enough food in its cell for its full development.

Leafcutting bees do not produce excrement in the usual way. They excrete their waste all at once, and wrap it in a cocoon inside the cell. They overwinter in this shelter, in what is called a “prepupal” stage (the final larval development stage). When warmer weather returns, the insect turns into a pupa and then an adult. Adults live from one to three months. Most species produce one generation a year.