Enallagma
anna
(River Bluet)
Description:
Naiad-This
is a small naiad ¾ to one inch (19 to 23 mm) long. It has the typical slender
shape of immature damselflies. They range in color from green to light brown.
Adult-This
is a small damselfly 1 ¼ to 1 ½
inches (31 to 37 mm) long. The males are predominately blue on the sides of
the thorax, and the upper side of the abdomen is predominantly blue, with black
stripes or dots on the upper surface of most segments. Females are pale blue
or tan, patterned very similarly to the males.
Range:
This species is found from
Wisconsin west to southern Idaho and Montana, and south to New Mexico and southern
California. In Idaho it occurs in the southern half of the state.
Habitat:
This damselfly occurs
at nutrient rich streams or rivers with slow to moderate flows.
Adult Flight Season:
June 18 to August
12
Diet:
Naiad-Naiads
eat a wide variety of aquatic insects, including mosquito larvae, mayfly larvae,
and other aquatic fly larvae.
Adult-Adults
eat a wide variety of small soft-bodied flying insects, such as mosquitoes,
mayflies, flies and small moths. They will also pick small insects such as aphids
from plants.
Ecology:
The River Bluet is usually
found in nutrient-rich streams in the sagebrush deserts of the western United
States.
Reproduction:
The males set up territories
at choice breeding sites. After males and females mate, the male remains attached
to the female (called "in tandem") as she oviposits in vegetation in streams
and rivers.
Conservation:
Populations
are widespread, abundant, and secure.
![]() |
![]() |
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 Unpublished M. S. thesis.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.