If you cut open a cell shortly after the bee completes construction you will
see a mass of pollen mixed with nectar, and an egg. The egg hatches, feeds
on the provisions, spins a cocoon, and overwinters in the last larval instar.
In the spring it pupates and emerges as an adult about the time that alfalfa
blooms.
Pollen balls are cells that contain uneaten pollen provisions, either because
no egg was laid, or because the egg or young larva died before feeding.
