Posts Tagged ‘exuviae’

“Odonate Larvae and Exuviae” Facebook group

November 29, 2019

I created a new Facebook group called “Odonate Larvae and Exuviae.” Readers of this blog who enjoy my photographs of odonate exuviae might be interested in following the new group. Please join us!

Copyright © 2019 Walter Sanford. All rights reserved.

Odonate exuviae collecting sites

July 29, 2019

The following video shows a “boater’s-eye view” of some sites where odonate exuviae have been collected by Joseph Johnston along Aquia Creek, located in Stafford County, Virginia USA. Joe is an avid boater and sport fisherman who kindly agreed to be my “Eyes on the Aquia,” always on the lookout for odonate exuvia to share with me.

The first photo gallery features still images of several spots shown in the preceding video. Joe estimates the water is ~5-6 feet deep outside the channel markers, and much deeper in the middle of the creek.

Joe’s boat is somewhere between the long boat docks (lower-right quadrant) and Government Island (near center), as shown in an aerial view of Aquia Creek provided by Google Maps.

The last photo gallery features still images of several exuviae, shown in situ before Joe collected the specimens. The first photo shows where it all began, when Joe collected his first dragonfly exuvia for me on 20 June 2018.

Related Resources

Credits

All media Copyright © 2019 by Joseph Johnston. Used with permission from Mr. Johnston.

Copyright © 2019 Walter Sanford. All rights reserved.

Composite image: Progomphus obscurus exuvia

February 4, 2019

The following focus-stacked composite image shows the exuvia from a Common Sanddragon (Progomphus obscurus) larva that was collected and reared by Bob Perkins.

I have 10s, maybe 100s, of Common Sanddragon exuviae in my collection, but have never seen one cleaner than this beautiful specimen. I didn’t realize P. obscurus larvae are so hairy!

Related Resource: More composite images: P. obscurus exuvia.

Tech Tips

11 photos were used to create the focus stack. A single focus point was positioned over select anatomical features, working from back-to-front; photos were taken at each point of interest.

The following equipment was used to shoot the preceding composite image: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (set for f/11 at 3x); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Auto power-off was disabled for the camera and all external flash units.

Adobe Photoshop CC 2017 was used to create the focus stack, as well as spot-heal and sharpen the final output.

Copyright © 2019 Walter Sanford. All rights reserved.

Top 10 Photos of 2018

January 2, 2019

The following gallery shows 18 finalists for my “Top 10 Photos of 2018.” The photos are presented in reverse-chronological order beginning in September 2018 and ending in February 2018.

No. 1

20 SEP 2018 | Fairfax County, VA | Pandora Sphinx moth

No. 2

23 AUG 2018 | Occoquan Bay NWR | Osprey (male, plus prey)

No. 3

No. 4

No. 5

No. 6

05 JUL 2018 | Fairfax County, VA | Sable Clubtail (female)

No. 7

No. 8

No. 9

12 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

No. 10

08 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

No. 11

06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

No. 12

No. 13

No. 14

No. 15

No. 16

No. 17

No. 18

Editor’s Note: The following location codes are used in some photo captions, shown above.

Copyright © 2019 Walter Sanford. All rights reserved.

Test shots: Unknown odonate exuvia

December 12, 2018

An odonate exuvia from an unknown species of dragonfly (Anisoptera) was collected by a good friend during April 2018 in Vienna, Austria.

Based upon the crenulations along the margins of the labium, I think the specimen is a member of either the Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers). I need to clean the anal pyramid for a clearer look at the terminal appendages in order to identify the family.

One-off

The first photo is a “one-off,” that is, not a composite image. The focus point is on the face mask/head; the rest of the subject is in soft focus.

Anisoptera (unknown species) | exuvia (face/head-dorsal)

Composite images

The next two “photos” are three-layer focus-stacked composite images: For each image, the focus point is on the face mask/head in the first photo; the thorax in the second photo; and the terminal appendages in the third photo. The entire body of the exuvia is acceptably in focus, including most of the legs.

The specimen has dorsal hooks on some abdominal segments (exact number unknown without closer examination), and lateral spines on abdominal segments eight and nine (S8-9).

Anisoptera (unknown species) | exuvia (dorsal)

I think this individual might be a female, as indicated by what appears to be a rudimentary ovipositor that is visible on the ventral side of abdominal segment nine (S9).

Anisoptera (unknown species) | exuvia (ventral)

Post Update

Sincere thanks to Benoit Guillon and Christophe Brochard, members of the “Dragonflies and Damselflies – Worldwide Odonata” Facebook group, for kindly identifying this specimen as an exuvia from a Downy Emerald dragonfly (Cordulia aenea). Downy Emerald is a member of the Family Corduliidae (Emeralds).

The following photo shows a plastic container of 20 Downy Emerald dragonfly (Cordulia aenea) exuviae, collected by a good friend during April 2018 in Vienna, Austria. Thanks to field marks shared by Benoit Guillon, I was able to quickly determine that all of the exuviae are the same species as the specimen featured in this blog post.

Related Resource: Cordulia aenea: exuviae (1/2), by Benoit Guillon.

Tech Tips

The following equipment was used to shoot all of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to create the two focus-stacked composite images, as well as spot-heal and sharpen the final output.

Copyright © 2018 Walter Sanford. All rights reserved.

Test shots: Tachopteryx thoreyi exuviae

November 30, 2018

Two Gray Petaltail dragonfly (Tachopteryx thoreyi) exuviae were collected on 23 May 2018 by Walter Sanford near a forest seep at an undisclosed location in Northern Virginia USA. Gray Petaltail is a member of the Family Petaluridae (Petaltails).

Although both specimens are similar, they aren’t identical. For example, twin rows of hook-like structures are clearly visible on the dorsal side of the abdomen on the lower exuvia, and almost invisible on the upper exuvia. The upper exuvia is dirtier and appears to be more “worn” than the lower one. Notice the “schmutz” on the face of the lower exuvia, probably a piece of leaf litter.

Both individuals might be male, as indicated by vestigial hamules that appear to be visible on the ventral side of the specimens.

Test shots of the specimens were taken using a relatively small aperture of f/16 for greater depth of field. Each photo is a “one-off,” that is, not a composite image. Focus stacks will be created sometime in the near future, after the exuviae are rehydrated, cleaned, and posed for better composition.

Tech Tips

The following equipment was used to shoot both of the preceding photographs: Canon EOS 5D Mark II digital camera, in manual mode; Kenko 20mm macro automatic extension tubeCanon EF100mm f/2.8L Macro lens (set for manual focus); and Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and several external flashes set for “Slave” mode including Canon 580 EX- and Canon 580EX II Speedlites and a Godox TT685C Thinklite TTL Flash fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen both images.

Copyright © 2018 Walter Sanford. All rights reserved.

Precious cargo

November 5, 2018

Odonates are aquatic insects. They spend most of their life as larvae that live in water; this stage of their life cycle can last from a few months to a few years. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

Careful and/or lucky observers will notice exuviae (sing. exuvia), also known as either “cast skins” or “shed skins,” left behind when odonate larvae emerge. Exuviae are fragile little works of natural art that are challenging at best to ship from one location to another.

The preceding photo shows a small plastic vial containing three odonate exuviae, received from Andy Davidson. All three exuviae are members of Family Libellulidae (Skimmers). From left-to-right, the following specimens can be seen inside the vial: Wandering Glider (Pantala flavescens); Eastern Pondhawk (Erythemis simplicicollis); Blue Dasher (Pachydiplax longipennis).

Andy packed the exuviae carefully inside a 15 ml centrifuge tube with a screw on/off cap; pieces of crumpled bubble wrap were used to separate the specimens inside the tube. A pair of tweezers was used to remove the bubble wrap. All three exuviae appear to be in perfect condition.

Editor’s Notes

Andy Davidson is a graduate student at Virginia Commonwealth University in Richmond, Virginia USA. Andy works with Dr. James Vonesh, his faculty advisor, and a team of researchers studying the ecology of James River rock pools. Andy’s research project is entitled “Predator-Prey Interactions in a Changing World.”

Sincere thanks to Andy for kindly sharing several exuviae saved from laboratory-reared odonate nymphs — I’m looking forward to creating new annotated identification guides for the specimens!

Copyright © 2018 Walter Sanford. All rights reserved.

Macromiidae larvae/exuviae are horny

October 4, 2018

A prominent horn on the face is a key field marker for all larvae/exuviae in the Family Macromiidae (Cruisers).

The first image shows the top of the head of an exuvia from an Allegheny River Cruiser dragonfly (Macromia alleghaniensis), collected by Mike Boatwright on 07 June 2018 at Otter Lake in Amherst County, Virginia USA.

07 June 2018 | Amherst County, VA | exuvia (head-horn)

The next photo shows the top of the head of an Allegheny River Cruiser larva reared by fellow Virginian Bob Perkins, providing an excellent view of both the horn and antennae (2).

Image used with permission from Bob Perkins.

Tech Tips

The following equipment was used to shoot the composite image of the exuvia: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (set for 3x); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode.

Adobe Photoshop CC 2017 was used to create the focus-stacked composite image from eight photos.

Bob Perkins’ photo of the larva, taken on 03 October 2018, was shot using a Canon EOS Rebel T3i camera body and Canon EF-S 60mm macro lens.

Copyright © 2018 Walter Sanford. All rights reserved.

Why focus stack macro photos?

April 17, 2018

Why focus stack macro photos? The answer is obvious: The difference between a single macro photo and a focus-stacked composite image is like night and day.

The first example is one of the better photos from a set of 13. It is the same photo that is featured in Hetaerina americana exuvia, my identification guide for American Rubyspot damselfly exuviae.

The last example is a composite image created using all 13 photos in the set.

You may not notice the difference in quality unless you look at the full-size version of both images. When you click on the images they open in a new tab automatically. Toggle back-and-forth between tabs and I think you will agree the composite image is clearly better than the single photo.

The Backstory

An American Rubyspot damselfly (Hetaerina americananymph was collected by Bob Perkins on 06 August 2017 along the New River in Grayson County, Virginia USA. The nymph was reared in captivity, albeit briefly, until it emerged on 09 August 2017.

Copyright © 2018 Walter Sanford. All rights reserved.

P. lividus prementum

April 11, 2018

The following image shows a composite of six photos of the prementum for an Ashy Clubtail dragonfly (Phanogomphus lividus) exuvia. The composite is one of at least two new images that will be annotated and used to update Phanogomphus lividus exuvia, my identification guide for Ashy Clubtail exuviae.

The Backstory

An Ashy Clubtail dragonfly (Phanogomphus lividusnymph was collected by Bob Perkins. (The date and location where the specimen was collected are unknown.) The nymph was reared in captivity until it emerged on 21 March 2017 and metamorphosed into an adult female. This specimen is the exuvia from the nymph. P. lividus is a member of the Family Gomphidae (Clubtails).

Tech Tips

The following equipment was used to shoot all of the photos for the preceding composite image: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (manual focus only, set for f/8 at ~3x magnification); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode; and Canon 580 EX- and Canon 580EX II Speedlites in “Slave” mode.

Adobe Photoshop CC 2017 was used to create the composite image by “round-tripping” with Apple Aperture.

Copyright © 2018 Walter Sanford. All rights reserved.


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