Gomphus graslinellus
(Pronghorn Clubtail)

Order: Odonata
Suborder: Anisoptera
Order Description:
Family: Gomphidae
Family Description: Clubtail

   Naiad- This is a large naiad with a maximum length of 1 1/8 inches (29 mm). The abdomen is widest at segment five. There is a curved hook on the top of each abdominal segment two through nine, and there is a single, rear-facing spine on each side of abdominal segments seven through nine.
   Adult- This is a medium-sized dragonfly with a length of 1 7/8 to 2 1/8 inches (47 to 53 mm). The face and thorax are olive green, with the thorax marked with dark brown stripes. The abdomen is dark brown to black and is marked along the top with a line of elongated, triangular-shaped marks varying in color from greenish to yellow. The underside of the tip of the abdomen is marked with yellow and is swollen as in other Clubtails.

This species is found from southern British Columbia east to southwestern Ontario, extending south to Washington, Oklahoma, and Missouri. In Idaho, it is found in the northern half of the state.

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

Adult Flight Season:
Early June to August

   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.

Clubtail naiads can be very selective in their habitat choice and will often occur only in certain stretches of a particular stream, lake, or pond. They burrow into the sand or mud, leaving the upturned tip of their abdomen exposed. This allows them to breathe while buried by pumping water in and out of the tip of the abdomen. These naiads emerge as adults at the water's edge just before sunrise. Although records are sparse, adults are believed to fly from early June to August. They can not tolerate cooler temperatures and are rarely seen flying on cool or cloudy days. Hunting occurs from perches on rocks or twigs.

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 rivers, lakes, or slow streams while hovering above it.

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.

HTML by Marty Peck, 2001.