Migrating with the darners!

We are "migrating" north to our VA farm tomorrow from SW FL and the most interesting natural event this morning locally was a virtual swarm of large greenish darners flying around at Cedar Pt park. The only one I could find on the ground is shown in an attached photo- I am guessing it is a juvenile green darner. Those odonatologists out there please let me know if I am wrong. I assume these are migrating from S FL or even the Caribbean, or possibly including d'flies which have just emerged from local ponds? There are quite a few large darner nymphs in local wetlands.
The question is do these dragonflies actually migrate to VA/NC- I am assuming this but wonder if they can over-winter as nymphs in VA? I know that the adult green darners abruptly leave our VA ponds in late Summer (and thus appear to be migrating) and are replaced by equally large shadow darners well into the Fall- I assume they are also migrating south but may be more tolerant of cold than the green darner.
So let us not forget that even "lowly" insects can do amazing things like migrate over long distances.
Cheers- Bill