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Species Pachydiplax longipennis - Blue Dasher

Pachydiplax longipennis - male Blue Dasher - Pachydiplax longipennis - male Blue Dasher - Pachydiplax longipennis - male Blue Dasher - Pachydiplax longipennis - male Blue Dasher - Pachydiplax longipennis - male Blue Dasher - Pachydiplax longipennis - female Female - Pachydiplax longipennis - female Dragonfly - Pachydiplax longipennis - female Blue Dasher - Pachydiplax longipennis - female Blue Dasher - Pachydiplax longipennis - female Blue Dasher - Pachydiplax longipennis - female
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Odonata (Dragonflies and Damselflies)
Suborder Anisoptera (Dragonflies)
Family Libellulidae (Skimmers)
Genus Pachydiplax
Species longipennis (Blue Dasher)
Other Common Names
Swift Long-winged Skimmer (apparently labeled as such in the Audubon Field Guide)
Blue Pirate (according to Needham, Westfall, and May)
Synonyms and other taxonomic changes
Pachydiplax longipennis (Burmeister, 1839)
Numbers
The only Nearctic species in the genus.
Size
25-43 mm
Identification
A small blue dragonfly with a white face, a black tip to the abdomen, and a black-and-yellow-striped thorax. Females are recognized by the narrow yellow parallel stripes on the abdomen. Both sexes have an amber patch at the base of each hindwing. Males develop a sky-blue (or Carolina-blue) abdomen when they approach maturity.
[description by Dragonflies and Damselflies of New Jersey]
California specimens turn blue not just over the abdomen (hiding the dark tip), but the thorax as well, and often have no amber on the wings at all.

Males:
Juvenile males show the female coloration before they turn blue.
  

"tweens" - As they mature the abdomen becomes blue except for yellow that remains on the sides of the first few abdominal segments and the black tip on the end of the abdomen. The eyes at this stage are still juvenile red/grey.
  

Fully mature males are powdery blue with jade-green eyes.
   .

The male secondary genitalia under abdominal segment 2 are evident:
  

While the male claspers at the end of the abdomen are clearly visible here.
  

Females:
- paired yellow stripes on the dorsal side of the first 8 abdominal segments, but not on segments 9 and 10. The end of the abdomen has a yellowish-white tuft in the center. Their eyes retain the half red/brown, half blue/gray color of immatures, though an occasional green-eyed female can be seen.
  
  
  

Females are also reported to turn blue with age, but more slowly than males. Older females get somewhat bluish, but never, it seems, quite like the males. See
  
  
Range
Much of the United States, and just edging into Canada. In the United States, absent from the Dakotas and the Rocky Mountain region. Range continues into Mexico.
Habitat
Ponds, lakes, marshes, and bogs. Can be found almost anywhere there is still water. Larva is highly tolerant of wetlands with poor water quality and low dissolved-oxygen levels.
Season
Primarily a summer species.
Food
Tiny flying insects.
Life Cycle
Mating takes place in the 'wheel' position.
  
Females oviposit (lay eggs) in the aquatic vegetation.
  
It's not unusual to see dashers infested by mites.
  
As they age, their wings are tattered from wear and tear.
  
Remarks
There's often amber color in the wings.
  
But western males with little amber in the wings and hardly any black on abdomen tip have caused identification confusion (even the thorax turns light blue):
  
  
but notice the blue-green eyes and black spot above the white face.
And this one with blue and white thorax is very unusual
  

Both genders often land with their wings cocked forward.
  
They sometimes orient themselves in different positions relative to the sun, either to maximize or minimize heat gain, depending on temperature. They tip the abdomen upward in what is called the "obelisk" position.
  
The thorax is striped, yellow and brown:
  
Notice the black spot surrounded by blue between the their white face and the blue-green eyes of the mature males. As do all dragonflies, they have excellent vision because of their large multi-faceted eyes.
Females and immature males:
  
Mature males:
  
Print References
Dunkle (1)
Internet References
live adult male and female images plus habitat, flight season, and links to similar species (Dragonflies and Damselflies of New Jersey)