Summer arrives this week and with it some of the most beautiful flying insects you will encounter in North America.
Not the butterflies (those are obviously gorgeous), but rather the dragonflies and damselflies. I’ve been seeing the occasional dragon and damselfly for quite some time now, but down by the stream that flows behind the house, I encountered my first big flight of ebony jewelwing damselflies this past week and knew summer was finally here.
The ebony jewelwing (Calopteryx maculata) is a large damselfly commonly found along shaded streamsides. The male has a brilliant iridescent body that can, depending on the light, appear green or blue with large, solid black (ebony) wings.
The females are more subdued, but no less lovely, with brownish bodies and smoky wings with a white rectangular spot (the pterostigma) on the front edge (hence the species name “maculata” meaning spotted). These large, dark wings are their most distinguishing feature, the reason for the genus name given to this group, Calopteryx, which means “beautiful wing.” Ebony jewelwings also have a fairly distinctive fluttery flight, with not as much zooming as other dragon and damselflies. It can sometimes be mistaken for that of a butterfly.
Damselflies belong to the same order as dragonflies, the Odonata, a word derived from two Greek words meaning “toothed jaw.” As the name suggests, these animals are fierce predators. They don’t bite humans, but are some of our most well-known mosquito-predators, both in the water and in the air.
The young live in the water, hatched from eggs laid on underwater vegetation in the summer. They overwinter in their aquatic form, climbing out of the water as they metamorphose into their adult flying form. The larvae are often at the top of aquatic food chains, especially when bigger fish aren’t present, and so are important for controlling mosquito larvae populations. This is one reason mosquitoes are often more successful breeding in small, stagnant pools of water like those that collect in old tires or buckets with no damsel and dragonfly predators to worry about. The adults patrol the air, snatching insects as they fly.
How to tell a dragonfly from a damselfly? Dragonflies hold their wings spread open at rest and have eyes connected across the top of their head like goggles. Damselflies have widely-spaced, separate eyes and hold their wings together above their body when at rest. One exception is the spreadwing damselflies (there are always exceptions in nature), these hold their wings open at rest. Dragonflies are usually larger and beefier than damselflies. Though at 2 inches, the ebony jewelwing is larger than many dragonflies. Its body is more slender and delicate.
If you find some ebony jewelwings by a stream, it is fun watching them interact. Damselflies are short-lived, living two to four weeks in the adult form, and are in the throes of mating. Males defend territories along slow-moving streams and will perform courtship displays like hovering in front of perched females, or perching in front of females holding the hindwings downward, perpendicular to the ground, while raising the forewings and abdomen forming a “cross display. It is thought that these displays are meant to draw attention to his wings. Females are more likely to pick males with darker wings to mate with because more wing pigment is correlated with larger bodies, more fat reserves and stronger immune abilities, allowing the males to more successfully defend territory along streams.
Like other odonates, damselflies mate in the air. If you see damselflies flying around attached to each other, this is what you are seeing. The male uses special claspers on the end of his abdomen to hold the female by her thorax while they are joined at the abdomen. This is called the wheel position. Though I’ve also heard it called “in heart” because their bodies make a heart shape. How romantic! If you see a damselfly repeatedly dipping her abdomen in the water, she is laying eggs.
Ebony jewelwings will be gracing our streams and other wetlands for the next couple months. They are small enough to go unnoticed, but I found, as is so often true, that once I knew what they were and where to find them, I went from never noticing them to seeing them everywhere. All you have to do is go out and look.
Susan Pike, a researcher and an environmental sciences and biology teacher at Dover High School, welcomes your ideas for future column topics. She is looking for readers to send her the signs of spring they're noticing so she can document them on her website pikes-hikes.com. Send your photos and observations to firstname.lastname@example.org. Read more of her Nature News columns online at Seacoastonline.com and pikes-hikes.com, and follow her on Instagram @pikeshikes.
This article originally appeared on Portsmouth Herald: Nature News: Ebony jewelwings arrive with their delicate beauty