Monday, July 4, 2016

Fragile Forktail Damselfly

Fragile Forktail female- Linda Bower
Dragonfly naiad - REK
If you ever wondered how an aquatic naiad (larva) of a damselfly can transform into an adult like the one above, this is your chance to see it happen.  You can watch as it pumps fluid into wing veins to expand them, then air into the abdomen.

Linda Bower of our Master Naturalists sent me the following study and videos of  her Fragile Forktail Damselfly, Ischnura posita.

If you spend any time at a local pond, you may miss the well-named Fragile Forktail Damselfly (FFD). It is almost the size of a straight pin, at less than an inch long. I found it with binoculars and the zoom on my camcorder and then became obsessed with filming it’s various activities. Admittedly, my camcorder faced it’s limitations with the FFD’s size, distance, and preference to stay in the shade.

FF male - Patrick Murray
The Fragile Forktail is distinguished from the very common Eastern Forktail by the shoulder stripes. The FFD’s stripes look like exclamation points. Additionally, the Eastern has blue at the tip of its abdomen, the FFD doesn’t. The females of the two species are almost identical and duller than the males. The FFD female also has interrupted shoulder stipes, but it is more difficult to see them. Don’t be fooled, these are voracious predators capable of capturing prey of their own size, including other damselflies.

Eastern Forktail - Fyn Kynd
This video shows a Fragile Forktail emerging from its larval stage (photo of emerging).  It was filmed from about 7 feet away, with my tripod stuck deep in the mud a few feet from shore. The process took a couple of hours. With editing software, I cut out all but 18 minutes and then sped up most of the clips. This reduced the video length to 1 minute 40 seconds. And then I added music to cover up my gasps and shrieks as I watched this happen for the first time in my life.

I have hours and hours of video showing the Fragile Forktail laying eggs and I’m still not satisfied with the footage. Apparently they don’t like to lay eggs near the shore. Still, it is fascinating to watch this video, which shows her size relative to a tiny Juniper berry.

Happily, I found a female eating lunch right next to where I was sitting. Any parent would be proud of how well she cleaned her face and hands after eating in this video.

My obsession will certainly continue through the summer. Stay tuned to my YouTube channel for more views of dragonflies and damselflies!

The process is explained by Naturally Curious with Mary Holland:

"At the end of its larval stage, a dragonfly larva crawls out of the water where it’s been living and climbs up onto emergent vegetation, or a nearby rock, where it clings as its skin splits along its back and head.  The adult winged dragonfly pulls itself out of its larval skin through this hole, and grasps the skin (or vegetation or rock) while it pumps its body full of air and sends fluid into its wing veins.  This fluid causes the wings to enlarge — the wing expansion that is evident in these two photographs took place in less than ten minutes.  When it first emerges from its skin, a dragonfly is pale and soft, and the wings have a characteristic pearlescent sheen, as in these photographs.  Within a day or so the wings lose this sheen, the body hardens and colors start to develop."

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