(Western River Cruiser)
Naiad- This is a large naiad 1 ¼ inches (30 to 32 mm) long. It has a large, rounded abdomen and long legs, giving it a spider-like appearance. There is a curved hook on the top of abdominal segments two through ten, and a single, rear-facing spine on each side of abdominal segments eight and nine.
Adult- This is a large dragonfly with a length of 2 ¾ to 3 inches (69 to 74 mm). The eyes are green. The thorax is greenish brown with a metallic luster and may be marked on the top and sides with yellow. The abdomen is black and ringed with yellow, but the rings do not completely encircle the abdomen. The tip of the abdomen appears swollen ("clubbed").
This species is found from southern British Columbia south to California and Arizona. In Idaho, it occurs in the southwestern corner of the state.
This dragonfly can be found near rivers with dense aquatic weeds. In Idaho, this species is found almost exclusively along warm-water rivers.
Adult Flight Season:
Mid-June to late 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.
The naiads live on submerged weeds and tree roots in rivers. They are ambush predators, waiting for prey to pass by. They emerge as adults during the night. Although records are sparse, adults are believed to fly from mid-June through late August. Adults hunt while on the wing, and fly at high speeds often down the middle of rivers and streams.
Males actively patrol in search of receptive females during the morning. After males and females mate, the females fly singly, without the male attached, to deposit their eggs. The tip of the abdomen is dipped into the water, typically a weedy river, while flying just above the surface. Both males and females disappear by early afternoon.
Populations are widespread, abundant, and secure.
|Status:||Unprotected nongame species|
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 Unpublished M. S. thesis.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.