Epitheca stella, commonly known as the Robust Baskettail, is a species of dragonfly belonging to the family Corduliidae (known as emeralds or baskettails). It is characterized by its relatively large and robust build compared to other species within the genus Epitheca.
Description Adult Epitheca stella typically measures about 50-60 mm in length, with a wingspan of 65-80 mm. The body is generally dark metallic green or bronze, often with a somewhat hairy thorax. The wings are clear, though some individuals may exhibit a faint amber or brownish tint at the base, particularly in the hindwings. The abdomen is robust, especially at the base, and tapers towards the end. Males possess distinctive superior anal appendages (claspers) used for gripping the female during mating. The eyes are typically a bright emerald green in life, though this fades after death.
Habitat and Distribution The Robust Baskettail is primarily found in western North America. Its distribution includes mountainous and forested regions from British Columbia in Canada south through parts of Washington, Oregon, California, and into other western U.S. states. It prefers habitats with clear, cool, and often swift-flowing streams and rivers, typically in forested or semi-forested areas. Larvae develop in the clean, oxygenated waters of these streams.
Life Cycle and Behavior Like all dragonflies, Epitheca stella undergoes an incomplete metamorphosis. The aquatic larvae (naiads) are predatory, feeding on other aquatic invertebrates. They spend multiple years in the water before emerging as adults. Adult flight periods typically occur from late spring to late summer, depending on the specific geographic location and elevation. Males often patrol stretches of stream in search of females. After mating, females deposit their eggs by dipping the tip of their abdomen into the water.
Taxonomy
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Odonata
- Suborder: Anisoptera (Dragonflies)
- Family: Corduliidae
- Genus: Epitheca
- Species: Epitheca stella (Williamson, 1901)