Pachydiplax longipennis
(Blue Dasher)

Order: Odonata
Suborder: Anisoptera
Order Description:
Family: Libellulidae
Family Description: Dasher

   Naiad- This is a relatively small naiad with a length of 3/4 to 7/8 inch (18 to 21 mm). It is brownish above and bright green underneath. There is a single, rear-facing spine on each side of abdominal segments eight and nine, with those on segment nine being noticeably longer. There are no hooks on the back, as some naiads have.
   Adult- This dragonfly is small to medium in size, with a length of 1 3/8 to 1 13/16 inches (35 to 45 mm), and has a fairly broad abdomen. Females and immature males are greenish on the face and thorax, with a brownish black abdomen marked along the top with two parallel lines of pale yellow to yellowish green dashes. Mature males are greenish on the face and thorax but the abdomen is pruinose blue. The wings are mostly clear but may be clouded with brownish yellow at the bases, especially on the hindwings.

This species is found from southern British Columbia east to Ontario, extending south through the U.S. from southern California east to Florida. It also occurs in the Bahamas. In Idaho, it can be found throughout the state at lower elevations, usually below 3000 feet (914 meters).

This dragonfly can be found near lakes, ponds and slow streams at low elevations.

Adult Flight Season:
Late June to October

   Naiad- Naiads feed on a wide variety of aquatic insects, such as mosquito larvae, other aquatic fly larvae, mayfly larvae, and freshwater shrimp. They will also eat small fish and tadpoles.
   Adult- The dragonfly will eat almost any soft-bodied flying insect including mosquitoes, flies, butterflies, moths, mayflies, and flying ants or termites.

The naiads live in submerged vegetation. They do not actively pursue prey but wait for it to pass by, a strategy which affords them protection from other predators. The naiads of this species can tolerate water with low oxygen content. This is used by biologists in Florida who interpret their presence as a possible indicator of low water quality. Naiads emerge as adults at night. Adults generally fly from late June to October. Hunting occurs from perches on twigs and rocks. This is the only member of this genus.

After males and females mate, the female flies singly, without the male attached, to lay her eggs by dipping the tip of her abdomen in the water while hovering above its surface.

Populations are widespread, abundant, and secure.
Status: Unprotected nongame species
Global Rank: G5
State Rank: S?

Corbet, P. S. 1999. Dragonflies: Behavior and Ecology of Odonata. Cornell University Press, Ithaca, New York, USA, 829pp.

Logan, E. R. 1967. The Odonata of Idaho. Unpublished M. S. thesis. University of Idaho, Moscow, Idaho, USA, 105 pp.

Needham, J. G. and M. J. Westfall. 1955. Dragonflies of North America. University of California Press, Berkely, California, USA, 615 pp.

Paulson, D. R. 1999. Dragonflies of Washington. Seattle Audubon Society, Seattle, Washington, USA, 32 pp.

Walker, E. M. and P. S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. III. University of Toronto Press, Toronto, Ontario, Canada, 307 pp.

Written by Mark Lung and Stefan Sommer, 2001
Photos by Dennis Paulson, 2001
Design by Ean Harker, 2001.