by Dennis McNair, PhD
Damselflies are sort of Dragonflies’ smaller cousins. The two are closely related to each other in systems of biological classification, both being in the Order Odonata (odonates) of the Class Insecta. Dragonflies are placed in the Suborder Anisoptera because their two pairs of wings are of different size and shape ("iso-" the same, “pteron” wing), and damselflies are in the Suborder Zygoptera because all four of their wings are similar ("zygo" together).
Damselflies are slender, fluttering insects, while dragonflies are generally fast-flying and robust. They are both predaceous on other insects (in both juvenile and adult stages), spend most of their lives in the water (the winged adult stage emerges, disperses, mates and dies), and their aquatic juveniles have a hinged, extensible, prehensile lower “lip” for capturing prey. Humans consider them beneficial because they prey on mosquitoes (and “lake flies” here at Chautauqua), although dragonflies seem to be more voracious predators than damselflies, probably because of their speed, size, and efficiency (researchers have shown dragonflies to be over 90% successful in capturing prey on the wing). Despite common myths, odonates have probably always consumed more mosquitoes than bats or Purple Martins.
The damselfly depicted in the photo accompanying this article was photographed by Jeanne Wiebenga as it perched on a plant stem near the lake. It’s likely to be a Marsh Bluet (Enallagma ebrium), one of the lovely sky-blue and black damselflies that are common, but require close examination of their reproductive structures to identify properly. Marsh Bluet larvae spend much their lives in ponds and small lakes, or along the edges of larger lakes, and the adults do a great deal of perching when not hunting. They have small blue eyespots, behind their remarkable compound eyes, that are connected by a line to form a “dumbbell” shape.
Ed Yong, in his book An Immense World, points out that odonates have as many as 15-33 “opsins” which register various frequencies of color (humans have 3, so try to imagine the range of “colors” odonates can see) and have visual fields covering almost 360 degrees. This, coupled with very rapid flicker-fusion, helps to explain why they’re so successful in catching prey and so difficult for collectors to capture in their nets. Their vision is incredibly acute, and, to them, we appear to be moving in slow motion!
We humans have always compared the perception and consciousness of other animals to our own, and modern research shows that we’re really very limited in that regard. Dogs can discriminate thousands of smell cues that we can’t, bats can navigate in the dark by echolocation, many insects can “see” far into the ultraviolet and infrared ranges where we are blind, mosquitoes locate us by sensing the carbon dioxide and heat we give off, etc.
Yong’s book is very useful (and humbling) in clarifying the abilities of other animals that humans lack. So, the next time you step on a “bug” or compare the size of your brain to that of a fish, think, at least briefly, about the faculties you lack and they possess. Also, Louis Comfort Tiffany recognized the beautiful patterns in odonate wings and incorporated them into his glass lampshades. Other artists and artisans have mimicked those and other natural patterns for centuries. The beauty and wonder Nature inspires are readily available to all of us every day if we take the time to look for it. Damselflies are just one, commonly ignored, example of such things.
If you're interested in learning more about Odonates, click here for Dennis's recommended reading list.
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