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stream bluet
stream bluet (Enallagma exsulans) [female] [male]
Photo © Mary Kay Rubey
Features and Behaviors
FEATURES
The stream bluet is very similar to several other bluets and only close inspection of coloration and black pattern will distinguish it from azure (Enallagma aspersum), skimming (E. geminatum), slender (E. traviatum), and turquoise (E. divagans) bluets. They are about 1.5 inches long and are sexually dimorphic. Males have black-topped blue eyes, a blue and black thorax, and a mostly black abdomen with a blue ring separating each abdominal segment. Females have a similar thorax to males, and a thicker abdomen that is black on top and blue green below. Females are especially like blackwater (E. weewa), rainbow (E. antennatum), and turquoise bluets.
BEHAVIORS
The stream bluet can be found all over Illinois, flying form May to September in medium streams to large rivers with lots of willow along the banks. It’s an abundant and widespread species. It appears resilient to pollution and persists even in degraded streams. Males hover over pools for long periods of time and perch on plants near the water. Pairs are often seen together near the water or in woodlands and take one to two hours to mate. Pairs fly together for about 30 minutes afterwards while the female lays eggs. Eggs are deposited near willows and below the waters surface in aquatic plants. Many bluets prefer lake habitats, but as the name suggests, the stream bluet is at home along moving water. Evolutionarily, having invaded aquatic habitats alongside dragonflies, this species has adapted to predation by developing longer caudal gills making them faster swimmers.
Illinois Range
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Family: Coenagrionidae
Illinois Status: common, native
