(1) Mature Larva - The Leafcutting Bee overwinters as a mature larva. Storage at 50�F prevents development.

(2) Pupa - When temperatures increase in the spring, the larvae begin to develop and pupate. Development is fastest at 86�F. The incubation period lasts from 3 to 4 weeks.

(3) Adults, first generation - The pupae give rise to adults which must chew their way out of their cocoons. Males emerge first after about 18 to 20 days of incubation. Females emerge from 21 to 24 days after incubation.

(4) Egg - Females mate immediately after emerging. They then select a hole and begin to provision cells. Eggs are present a few days after females begin flying. A female can construct one to two cells per day, depending on conditions. Each cell is made up of a leaf-lined cup packed partially with pollen. The bee deposits a small droplet of nectar on the surface of the pollen and lays the egg in the nectar.

(5) Mature Larva - Larvae reach maturity in about 3 weeks, depending on temperature. The larva will then either proceed into diapause (a hibernation-like state in which they overwinter) or they will continue developing to produce a second generation.

(6) Pupa - When pupae are found in the nests, they will inevitably hatch as second generation adults. In warmer climates such as California, 40 to 80% of the larvae may develop into second generation.

(7) Adult - These second generation adults appear about a month after eggs are laid. These adults will readily use the nest holes from which they emerged.

(8) Egg - Eggs are laid by second generation adults within a few days of nesting. These eggs will hatch and the larva will mature and go into diapause. A small percentage will continue to develop and create a third generation. These adults emerge in late August and September, too late for alfalfa pollination. The diapausing larvae can then be held in cold storage until the following spring when they can be incubated.