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Friday, June 20, 2014

Dancing Damselflies

Desert Firetail, Telebasis salva

Often overlooked but in the same Order (Odonata) as dragonflies, damselflies are a group of insects that differ from dragonflies by wing shape, wing position, and eye separation.  Damselflies have similarly shaped fore and hind wings, typically hold their wings together over their abdomen when perched, and their eyes are widely separated but never touching.  In comparison, the hind wings of dragonflies are broader basally than their fore wings, they hold their wings spread out and away from their body, and their eyes are much larger and usually touch at least at a single point. 

Amethyst Dancer, Argia pallens

While damselflies are less robust fliers than dragonflies, they are still quite agile in flight.  They can move each of their four wings independently, and can not only beat them up and down, but also rotate them on their own axes.  Most damselflies fly by alternating the two pairs of wings, and while one is moving down to propel them forward, the other is moving up.  In spite of their fast wing beats, damselflies have relatively short, narrow wings that don’t allow them fast flight, and they move at an average speed of about 2 meters per second.  

Rambur's Forktail, Ischnura ramburii

Over 75 species of damselflies occur in Texas, more than half of the known species in North America.  These species represent members of all families of damselflies, which include broad-winged damsels (jewelwings and rubyspots), spreadwings, threadtails, and pond damsels (dancers, bluets, yellowfaces, wedgetails, damsels, forktails, swampdamsels, sprites, and firetails).  Like most dragonflies, the males are usually the most colorful and the easiest to identify.

American Rubyspot, Hetaerina americana

Springwater Dancer, Argia plana

Usually inhabiting small seepages and springs, the Springwater Dancer (Argia plana) is one of the most common pond damsels in our area, and has a blue head, face, and eyes, and a blue thorax with a black dorsal (top) and shoulder stripe.  Its abdomen is also predominately blue, with black rings on most middle segments.  It can often be found along roadsides, away from water.  The Great Spreadwing (Archilestes grandis) is the largest damselfly in Texas and the US, and is recognized by its blue eyes, the metallic green stripes on the top of its thorax, and bright yellow stripes on its sides.  Its wings are clear to slightly smoky, often with darker tips.  Found around bodies of standing water, it perches in a distinct manner on vertical stems with its body hanging downward and its wings partly spread.  Common around open streams and rivers, the American Rubyspot (Hetaerina americana) is a broad-winged damsel that has a metallic red thorax, a metallic green abdomen, and a vivid red patch at the base of its wings that grows larger with age.    

Great Spreadwing, Archilestes grandis

Observed throughout the summer at almost any body of freshwater, damselflies are slender and delicate.  They seem to dance around and about the water, marked with colors of the rainbow, delighting all those who take the time to get to know and admire them!