She didn't tell me why. Dragonflies and damselflies perched or hunted or just generally flew near every body of water I visited, including the pool at my motel. I understand from the small insects that I have interviewed that dragonflies are so nightmarishly frightening that most species of insect do not sleep. Instead of sleeping, they are eaten. You can click on this picture to see a big version.
Damselflies have great big eyes, tremendously powerful wings, and fancy svelte bodies.
If you were designing a lethal airborne fighter and you had 3500 million years in which to do it, you would come up with a damsel fly. Two common kinds of mesquite live in most of the Sonoran desert. I think this is honey mesquite, Prosopis glandulosa . The other mesquite is called screwbean mesquite or Prosopsis pubescens . It has similar leaves and I forgot to write down which one this was.