Mason bees emerge from winter hibernation when temperatures rise to 50+ degrees in early spring. Males will emerge first and the females will emerge 1-2 weeks later. The males are much smaller than the females and only live for about two weeks, whereas, the females will live about 4-6 weeks. The males eagerly await for the females to emerge. Once they connect, the female will store the semen from mating and only uses it to fertilize the egg if she wants to get a female offspring. An unfertilized egg will become male. Female mason bees will lay about 15-20 eggs in her lifetime.
Here are some videos to learn more: