Spectacular photograph!
You have all of the critter in good focus and a pleasingly out of focus background... hard to do.
I agree with francois, the diagonal composition is strong.
As for the identification, I agree that this is a widow skimmer.
However, I think that it is a female based on the terminal appendages... i.e. the distal end of the abdomen. In males (immature or not) the tip of the abdomen tapers to a very thin point. In the female, the tip of the abdomen is fairly wide as it is in this individual.
Also, in my experience, most immature males show at least a hint of the white wing coloration that is present when they are mature. Although this may be this is absent in very, very young individuals. I am not sure.
Identification and sexing odes is not easy. I have been doing this for going on two decades and regularly have unsolved or incompletely identified individuals.
It is worth noting that that some species are nigh impossible to distinguish from (even very good) photographs as the distinguishing features are only seen by examining the terminal appendages under a (10x or 20x) hand lens. This, of course, means having the individual in hand. This is especially true for damselflies but also applies to some groups of dragonflies.
Regards,
--- Frank (
www.gorga.org/blog)