Macromia
magnifica
(Western River Cruiser)
Description:
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").
Range:
This species is found from
southern British Columbia south to California and Arizona. In Idaho, it occurs
in the southwestern corner of the state.
Habitat:
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
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:
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.
Reproduction:
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.
Conservation:
Populations
are widespread, abundant, and secure.
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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 Unpublished M. S. thesis.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.