Cordulegastronomy

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Filed under Outdoor Notes

June 6, 2011

Actually, this is a note about dragonflies, but it starts with a fly, a stink fly, (Coenomyia ferruginea), as unlovely as a large fat fly can be.

Stink Fly

"Rusty Stink Fly"

No, I’m not that good at insect identification; it’s just that a young lad once brought a dead one to church in a jar and asked me to identify it. After a few hours of struggling through dichotomous keys and a consultation with a real entomologist, I identified it as Say’s Stink Fly .

Now, according to the experts at Bugguide.net, that common name no longer applies; in fact, there is no common name. Therefore, I have decided to call it the “Rusty Stink Fly.”

This is a big fly, as big as a horsefly.

As I was mowing the lawn the other day, a large dark dragonfly, boldly marked in yellow, landed beside me in some ferns. I wasn’t certain as to exactly what species, but I was certain that I had never seen one like it before. I shut off the motor, ran and got my camera, and ran back.

The dragonfly had left. They always do.

I should probably just stop running.

Pretty disappointing.

That afternoon, I took the opportunity to drive out into the Tuscarora State Forest to see what I could see—and yes, I went over a mountain.

What I saw first was a Rusty Stink Fly.

Then I saw a large dark dragonfly boldly marked in yellow.

Pretty exciting.

In fact, I saw several of them, and I was able to get some pictures, which I identified as Twin-spotted Spiketails (Cordulegaster maculata), an inhabitant of clear headwater streams and pools.

Twin-spotted Spiketails (Cordulegaster maculata)

Twin-spotted Spiketail (Cordulegaster maculata)

In general, these spiketails cruised low around the foliage along the edge of sunny open areas, picking off flying insects. I managed to photograph one that had caught a very large fly, a rusty-colored fly—as big as a horsefly—which it took to a dead limb hanging over the creek to eat.

I couldn’t be sure, but it looked like the dragonfly was eating a Rusty Stink Fly.

Twin-spotted Spiketail eating, close up

Twin-spotted Spiketail eating

One of the things I love about digital photography is the neat stuff you discover once you download the photographs. I was lucky enough to get a good shot of the fly’s wing that I could compare with other photographs. Happily, there is a funny-looking North Carolina-shaped cell in mid wing, and, happily, there is actually a drawing on the Internet of a Stink Fly wing that shows the same funny-looking cell.¹

So, there you have it, a little bit of natural history. The Twin-spotted Spiketail (Cordulegaster maculata) emerges from clear headwater streams in late spring to hunt flying insect prey—to include insects as large as the “Rusty Stink Fly” —(Coenomyia ferruginea) along the edge of open areas.

Stink Fly (Coenomyia ferruginea) wing pattern

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One Response

  1. Dennis Murphy said:

    Ok, this is pretty amazing. You must be hyper-attuned to nature to capture these thoughts.

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