Eastern-tailed blues are so-called because they have a tiny little tail off the edge of their wings, although it is shorter than the “tail” of the longer true hairstreaks.
This one was exploring the clover in a little park near me, and finally found a poof of an elderly blossom that was to its liking. It rubbed its wings together, showing the iridescent blue of its dorsal wing (a relatively new word for me, just meaning the inside or top of the butterfly’s wing).
There are some theories floating around out there for why butterflies rub their wings together. So far, I’ve seen that they are making noise by rubbing their wings together (like crickets) and that it is to stay warm (heat friction). The two slightly more convincing reasons for this behavior is that it releases pheromones to attract mates, and that the tails and bright spots on the ends of their wings imitate the movement and appearance of a head. The tails are “antenna,” the orange dots are the “eyes,” and if a predator goes for the butterfly it is more likely to get a bite of the less-crucial back wing of the butterfly rather than its real head.