Pachydiplax longipennis
Blue Dasher is an attractive, active, pond-loving dragonfly. Males perch above the pond, actively dashing out after prey or to defend their territory, and then return to their favored perch.  

Blue Dasher typically perches either with its wings hunched forward (photo at top of page) or wing wings swept back (just above), and readily takes the "obelisk" position (as above) on hot days to thermoregulate. All these positions give it a certain charismatic appearance, like a jet fighter ready to launch.

Blue Dasher often frequents the same ponds as Western Pondhawk, and the mostly blue males are similar. Blue Dasher, though, has a white face and green eyes – rather than a green face and dark blue eyes – and does not perch on the ground like the pondhawk.

Photo (very top & below) 1 July 2006 Hastings NHR
Photo (just above) 24 July 2006 Arroyo Seco

Female Blue Dasher (above & left) can take on the charismatic poses, but she is patterned in yellow with black (racing) stripes, both on the thorax and abdomen. Her eyes are green but suffused with brown, but she has a white face like the male.

Photo (above) 24 July 2006 Arroyo Seco
Photo (left) 5 Aug 2006 Arroyo Seco

Immature males start out like females but rapidly gain the blue pruinescence over the abdomen and front of the thorax. It is the sides of the thorax that are last to color in, producing a blue male with dark-and-pale yellow racing stripes on its thoracic sides. In this individual (right), the eyes have also not gained their rich green color.

In eastern populations, even full adult males retain the stripes on the sides of the thorax (Beaton 2007). Here in the West, some males become all-blue but others do not. Eye color may be a better character to judge full maturity.

From underneath (below), such young males often may show many characters of immaturity, including a black-and-yellow abdomen and rusty coloration at the rear of the thorax, or at the base of the abdomen. However, even full adult males can show that latter feature.
Photo (above) 24 July 2006 Arroyo Seco
Photo (below) 20 June 2006 near Chico, Butte Co.

The size of Blue Dashers can change dramatically over the summer. Early emergers (like the young male just above) are quite large compared to those that emerge later in the season.

Since the first Blue Dasher was collected in MTY in 1963, the Arroyo Seco Lakes – next to the Arroyo Seco Campground – have been the center of local occurrence, with many observations from that locale (and many photos shown on this page). Upon to 30 individuals have been seen on dates in July and early August. However, the species is likely widespread in appropriate habitat throughout the county.

The map shows a selection of sites at which Blue Dasher has been observed. It may be widespread throughout the county in the lowlands, although as yet no records are right near the coast. It is possible that the species doesn't like the summer fog so typical of our coast.

In MTY flight dates stretch from 20 May to 10 Aug. Elsewhere in California flight dates span nearly all months, from Feb–Nov (Manolis 2003), so its flight span in MTY is likely longer than currently reported.

Literature cited:
  • Beaton, G. 2007. Dragonflies and Damselflies of Georgia and the Southeast. Univ. Georgia Press, Athens GA.
  • Manolis, T. 2003. Dragonflies and Damselflies of California. Univ. of Calif. Press, Berkeley.

Web resources:
Major identification web sites with much information on California odes include:

For sites with excellent photos to compare for identification or to simply enjoy, see: Many of these sites have links to other useful pages. Kathy Biggs's site is particularly useful in her selection of links.

All photos © Don Roberson 2007


Page created 20 Mar 2007