Species are shown alphabetically within taxonomic level. If you see an error, please let me know via the contact tab at the top of the page.
Aeshnidae: Common Green Darner (Anax junius)
In my picture of a pair in tandem, the female is also ovipositing (laying eggs).
Gomphidae: Russet-tipped Clubtail (Stylurus plagiatus)
This species has the habit of hanging vertically off the tips or edges of leaves. I'm calling this example an immature female because the mature females have blue eyes. The males have pronounced "clubs" at the ends of their abdomens, but on the females this feature is almost absent.
Libellulidae: Western Pondhawk (Erythemis collocata)
Libellulidae: Widow Skimmer(Libellula luctuosa)
One way to tell female widow skimmers from immature males is, the females have dark wingtips and the males don't.
Libellulidae: Common Whitetail (Libellula lydia)
Libellulidae: Twelve-Spotted Skimmer (Libellula pulchella)
This dragonfly's name refers to the three black spots per wing (times four wings).
Libellulidae: Flame Skimmer (Libellula saturata)
Libellulidae, Blue Dasher (Pachydiplax longipennis)
Blue dashers have pale faces. The adult males have blue bodies, a bit of amber color at the wing bases, and turquoise-colored eyes. Adult female blue dashers have black and yellow bodies and red upper eyes. As adult females grow older, their eyes also turn turquoise; in one image, an older female rests on a prickly pear fruit.
Libellulidae: Eastern Amberwing (Perithemis tenera)
One way to identify this species is to notice how small it is. Also, notice the white stripes on the abdomen and the greenish spots towards the front.
Libellulidae: Variegated Meadowhawk (Sympetrum corruptum)
Libellulidae: Black Saddlebags (Tramea lacerata)
Calopterygidae: Rubyspot (Hetaerina)
The common name refers to the red at the bases of the male's wings.
Coenagrionidae: Sooty Dancer (Argia lugens)
Coenagrionidae: Powdered Dancer (Argia moesta)
Coenagrionidae: Aztec Dancer (Argia nahuana)
Note how the blue bands on the Aztec Dancer's abdomen go all the way around, while the Arroyo Bluet's abdomen (below) is topped with black.
Coenagrionidae: Blue-Ringed Dancer (Argia sedula)
Coenagrionidae: Dusky Dancer (Argia translata)
One identifying characteristic of fully mature male dusky dancers is their blue eyes. In my photo of a mature male there's only a hint of that eye color, I suspect because of the low light.
Coenagrionidae: Arroyo Bluet (Enallagma praevarum)