The alfalfa leafcutter bee was introduced into the United States from Eurasia. It was believed that they were widely distributed during and after the World War II with the shipped crated war materials. They were able to develop large populations because of favorable conditions in the western United States. The alfalfa leafcutter bee consists of solitary working female bees and males that are used only to mate, then they disperse from the females. The females are approximately the same size as the common honeybees, but are darker with light bands on the abdomen.
Females spend the night in their nests facing inward.
They are unusual in that they dig out nesting areas, create nest cells, and provide food to their young. They line these cells with leaves, pebbles, or resin. To line their cells, the leafcutters prefer older alfalfa leaves, but they use sweet clover, lambsquarters, and flower petals from other species of plants. After the leaf is cut with their mandibles, they roll it between their legs for transport. Commercially, the nesting tunnels used are nesting boards.