Like you pointed out, they eat other insects. I'm sure it is the insects in your area they are attracted to. I'm not that close to the water, but I get clouds of them. I love seeing them too for the voracious insects eaters they are.

Dragonflies can and do travel pretty far distances from the body of water in which they were born. The adults are not aquatic. I see them in my yard all of the time, and there's not any water for miles.

They feed on other insects, which they find aplenty in a healthy garden.

I can usually get a dragonfly to step onto my my finger and perch there. I just move extremely slowly so as to show no threat. I love these creatures.

We have SO many dragonflies in our yard & I think it is because of not only all my flowers but also the small fish pond where they lay their eggs .. lots of their larvae (?) in the pond in summer. An area near Roswell, NM (Bitter Lakes?) is famous I believe for the number of different varieties of the dragonflies that are there.

I'm not really sure of the different varieties, but the ones in our yard seem to be mostly a golden/orange color here in Albuquerque, NM

Are fascinating, aren't they?!