Odd behavior

Carpenter bees being weird.

I had carpenter bees overwinter in in my garage. (Inside an empty bee condo - the same one carpenter bees seemed to use for squatting in (?) last June..) This is normal behavior because females for the next generation are laid late in the year and they have to overwinter as adults. Kind of like bears hibernating. Most bees "overwinter" as larvae/pupae and aren't actually aware of the process. 

This spring, when I brought their hiding place outside, I expected them to fly away. But they didn't... they stayed burrowed inside empty sticks, even after it turned warm. In a few weeks a male joined them - he hung around much longer than would be expected for a 'quick' visit.

The male is still there. And at least one female makes trips during the day - coming back and forth to the same stick, but without pollen..... I don't get it.

Carpenter bees (these are Xylocopa tabaniformis) drill fresh holes in wood for their nests. They aren't known to live in hollow sticks or cavities, but whatever.. bees have confused me before.

Males and females of X. tabaniformis look different. Females are 100% black, shiny metallic. The males, as pictured below, have blue/grey eyes and a furry thorax. They make great pets.