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river bluet
river bluet (Enallagma anna)
Photo © Paul Dacko
Features and Behaviors
FEATURES
The bluets are the most diverse North American genus of dameselflies and they all have varying amount of blue to black coloration, the river bluet is no different. They are one to one-and-a-half inches long, have long legs, and spots of blue behind eyes that don’t connect. Males have blue eyes with black caps; a blue and brown thorax with wide, black stripes on top, and narrow stripes on sides; a U-shaped marking near the base of the thorax; and their abdomen is black and blue. Females have two appearances (polymorphic) and tend to have more robust abdomens than males. The first morph has eyes that are brown on top, and cream colored below; a white thorax with a large, black stripe on top and thin, black stripes on the sides; and an abdomen that is white with black spots along top. The second morph has green eyes that are black on top; a blue thorax with similar black stripe pattern described in the other morph; and an abdomen that is blue and black. This species is very similar to the Alkali (Enallagma clausum) and Tule (Enallagma carunculatum) bluets. Males are differentiated from tule by unconnected post-ocular (behind the eye) spots but need to be examined in hand to be distinguished from the Alkali bluet. Females can only be distinguished in hand from Familiar and Tule bluets.
BEHAVIORS
This species inhabits small streams and rivers in open areas along the Northern border of Illinois and counties near the Lake Michigan shoreline. They can be seen flying June through September. They spend lots of time perched on plants on or alongside the river or stream. Females identify males of their species with sensory organs on their thorax. Females may submerge several inches under the water for up to 30 minutes to deposit eggs.
Illinois Range
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Family: Coenagrionidae
Illinois Status: common, native
