Saturday, October 14, 2017

Species Spotlight: Blue-eyed Darner

The Blue-eyed Darner is one of the easiest darners to identify—even on the wing the intense blue color of their eyes, and the blue stripes on their thorax, are a dead giveaway. Here's the spread on the Blue-eyed Darner in my field guide Common Dragonflies and Damselflies of the Pacific Coast:



The flight picture above shows the blue eyes and the blue thorax stripes that jump out as this dragonfly zips by you on a warm summer afternoon.

Also, notice the photo of the female in the lower right corner of the spread. It shows a "bump," or "tubercle," under segment 1 of the abdomen. This is a distinctive feature of Rhionaeschna darners—commonly referred to as neotropic darners—though it is not always easy to see or photograph. My picture was taken at Butchart Gardens, where a female Blue-eyed Darner flew in and landed on a structure in the middle of a water fountain at just the right angle to show the bump. Mosaic (Aeshna) darners lack the tubercle.

Here's a view of another distinctive feature of Blue-eyed Darners—the forked appendages on the males.



No other male darner has forked appendages, so it's a great field mark—not that it's really needed!

The next photo shows an interesting feature that is present in all darners, but is particularly noticeable in Blue-eyed Darners. It is the small, sharp projection on the front of the thorax, just behind the eyes. This is an "egg tooth" that these darners use to break through their larval skin during emergence.





The Blue-eyed Darner is indeed a study in blue. They perch often in sunlit bushes near the shore, and are very cooperative photographic subjects.



One final feature that distinguishes neotropic from mosaic darners is shown in the next photo. Notice the light area on either side of the black "T-spot". This is found in neotropic darners, but not in mosaic darners.





So many interesting features to look for next time you're identifying darners!

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