Stylurus (Gomphus) olivaceous
(Olive Clubtail)


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

Description:
   Naiad- This is a large, slender naiad with a maximum length of 1 ½ inches (36 mm). There is a short, rear-facing spine on each side of abdominal segments eight and nine.
   Adult- This is a medium to large dragonfly with a length of 2 ¼ to 2 ½ inches (56 to 60 mm). The eyes are a remarkable turquoise blue. The face and thorax are olive green, and there may be some black markings on the top of the thorax behind the head. The abdomen is brownish black and is marked along the top with yellowish, funnel-shaped marks. The underside of the tip of the abdomen is also marked with yellow, and the rearmost segments appear swollen as in other members of this family. The female may be more yellowish green than olive green, and may have more yellow on the sides of the abdomen.

Range:
This species is found from southern British Columbia south to central California and east to Nebraska. In Idaho, it occurs along the Snake River from Massacre Rocks near American Falls downstream, and along the Bear River.

Habitat:
This dragonfly can be found at large, nutrient-rich rivers.

Adult Flight Season:
Early August to mid-October

Diet:
   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.

Ecology:
Naiads can be very selective in their habitat choices and will often occur only in certain stretches of a particular river or stream. 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. Unlike most other species, the Clubtail naiads emerge as adults during the day. Adults generally fly from early August to mid-October. They perch on trees and bushes, often far from the water.

Reproduction:
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 it. This is usually done in large rivers.

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

References:
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.