The blue on these mature dragonflies (I believe the top image is a Blue Dasher and the next is a Great Blue Skimmer) is called “pruinescence”. Often described as a powdery accumulation of pigment, the phenomenon of pruinescence is not confined to dragonflies. (I couldn’t find a definitive resource for a link, but this Wikipedia article contains some interesting observations.)
I tend to gravitate toward pruinose dragonflies, when I’m out with my camera. I like how the pale coloration exposes seams and joints, highlighting the intricate anatomy of these amazing insects.
(This male Great Blue Skimmer was a very patient subject. Most of my dragonfly photos are taken using the zoom feature, but he let me experiment with the macro setting, which produced the next image.)
While coloration and wing patterns catch my attention first, wounds hold my attention. This female Great Blue Skimmer has a rather typical set of wing tears, but the wounds on her face are unusual. I wondered if the loss of symmetry made her less attractive, in dragonfly terms.
One final note (completely off-topic): I’m happy to report that the summer’s first cicadas arrived this week.