One day when I came home after some thunderstorms and was looking at the cup plants, I noticed that although some bumblebees were flying around and feeding from the flowers, others looked like they were hiding from something.
I did a little research online to see if bees take naps, and there are actually quite a few people that have blogged about this after observing the same thing I did. Although I couldn't find any scientific sources besides Wikipedia, one blogger said she looked this up and found out that female worker bumblebees are more actively looking to feed so they can bring food back to their nest for the queen and larvae (they don't create as large of colonies as honeybees do), but male bumblebees, once they are mature, do not go back to the nest. Their only purpose is to find a queen to mate with and reproduce. Since they don't need to bring food back to the nest for other bees, they rest when it starts to get cold and sleep through the night until the sun warms them up in the morning.
So this means I probably saw male bumblebees sleeping and female worker bees nectaring on flowers! Pretty cool.