Pachydiplax longipennis (Blue Dasher)

Male Pachydiplax longipennis (Blue Dasher)

Pachydiplax longipennis is the sole member of their monotypic genus of skimmers (Libellulidae). It is a medium sized dragonfly (total length 35-42mm), and both males and females develop a heavy pruinosity, although it is heavier in the males. The heavy pruinosity doesn’t quite obscure the green striped black thorax, or the black tipped abdomen. And you can always see the white face, and green eyes. They also have amber patches at their wing bases. 

Male Blue Dasher

Blue Dashers can be very abundant in early summer, especially at shallow, weedy lakes and ponds. Their larvae have a higher than normal tolerance for pollution and low oxygen levels. They are perchers , who like being right above the water, and they do not perch on the ground like Western Pondhawks ( Erythemis collocata), which is our only other species of small dragonflies with pruinose blue males and green females. They are fairly easy to differentiate because Western Pondhawks have a green face and unmarked thorax, as opposed to the white face and green striped black thorax of Blue Dashers. 

Pachydiplax longipennis

They can be found region wide, and fly from mid May into October. 

Pachy means ‘thick’ in Greek, and a diplax was a cloak, which I assume is a reference to the thick coating of pruinosity for which this species is known. The species epithet longipennis means ‘long wings’ in Latin, which is only applicable to the females, whose short abdomen makes them appear to have long wings.

Male Blue dasher

Size- 35-42mm total length 

Habitat- Slow or still water with abundant vegetation 

Range- Region wide 

Eats- Small flying insects 

Flight Season- May to October 

Male Pachydiplax longipennis (Blue Dasher)

2 thoughts on “Pachydiplax longipennis (Blue Dasher)”

  1. Saw my first Blue Dasher (that I was able to photo and identify) this past June at a pond at Helen McCabe State Park, north end of the Yakima River Canyon. Not knowing much about these guys, I had previously thought Blue Dashers and Blue-Eyed Darners were the same thing
    , but once you start paying attention, they obviously are not!

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