Aeshnidae exuvia

An odonate exuvia was spotted on 14 August 2012 along the boardwalk in the central wetland area at Huntley Meadows Park. The specimen was broken into three pieces when I found it: head and thorax; wing pads; and abdomen.

This individual is a member of the Family Aeshnidae (Darners). Here’s the decision tree I used to tentatively identify the exuvia as a member of the Darner Family.

• The specimen has a flat labium that doesn’t cover the face (not mask-like).
• Antennae are thin and thread-like (not club-like, as in Gomphidae).

Photo Set 1

Notice the labium is flat and isn’t mask-like, that is, doesn’t cover the face of the larva/exuvia.

Head and thorax (lateral view).

(See a full-size version of the original photo, without annotation.)

Also notice the antennae are thin and thread-like, as shown in the following annotated image.

Head and thorax (dorsal side).

(See a full-size version of the original photo, without annotation.)

The shape of the mentum and prementum (especially the rounded palpal blades) indicates this specimen is a Common Green Darner dragonfly (Anax junius), one of the more common species of Aeshnidae found at Huntley Meadows Park.

Head and thorax (ventral side).

(See a full-size version of the original photo, without annotation.)

Photo Set 2

The next photo shows the wing pads as well as part of abdominal segment one (S1). All odonates have a 10-segmented abdomen. The anterior side is toward the bottom of the photo; posterior toward the top.

Wing pads (dorsal view).

Abdominal segments two through 10 (S2-10) are shown in the following photo.

Abdomen (dorsal view).

Lateral spines along abdominal segments seven, eight, and nine (S7-9) verifies the genus and species as Anax junius. Notice the faint feature on segment nine (S9), highlighted by a white circle. This is a “rudimentary ovipositor,” according to SueandJohn KestrelHaven, active members of the “Northeast Odonata” Facebook group. An ovipositor is used for egg-laying by all adult damselflies and some species of adult dragonflies: females have this feature; males do not.

Abdomen (ventral view).

(See a full-size version of the original photo, without annotation.)

Related Resources

• Vimeo video: Identifying dragonfly larva to family (8:06)
• Anatomy of a Dragonfly Larva, annotated illustration courtesy Jay Smith
• Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz.
• Odonate Exuviae, by Walter Sanford

Tech Tips

The following equipment was used to shoot the preceding photographs:

• Photo Set 1: Canon EOS 5D Mark II digital camera; 50mm lens (“Nifty Fifty”) plus Raynox DCR-250 close-up filter; Canon 580EX Speedlite (ETTL mode) off-camera, using a pair of Yongnuo YN622C II Wireless Flash Trigger Transceivers; and a Nissin i40 (off-camera, in SF mode).
• Photo Set 2: Fujifilm X-T1 digital camera; Fujinon XF18-55mm (27mm-82.5mm, 35mm equivalent) zoom lens plus “Fotasy” brand 10mm extension tube; Fujifilm Shoe Mount Flash EF-42 (on-camera, in TTL mode); Nissin i40 external flash unit (off-camera, in SD mode).

Adobe Photoshop CC 2015 was used to annotate selected images.

The following photo reveals a behind the scenes look at my low-tech solution for staging specimen parts: a plastic toothpick (tan) from a Swiss Army knife held by a small plastic clothespin (green); both parts were held by an alligator clip (silver) mounted on a short, flexible arm.

All specimens were staged in front of the same opaque white plastic background. Hard to believe, huh? I own an 18% gray scale card; at some point, I should start using it to adjust the white balance in my macro photos!

Related Resource: Odonate Exuviae – a hyperlinked list of identification guides to many species of odonate exuviae from seven families of dragonflies and three families of damselflies.

Copyright © 2016 Walter Sanford. All rights reserved.

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Tags: Anax junius, Common Green Darner dragonfly, exuvia, Family Aeshnidae (Darners), female, gear talk, Huntley Meadows Park, wildlife photography