Posts Tagged ‘exuvia’

As promised…

August 9, 2020

A rare weekend blog post

The following photo was taken by tethering my Fujifilm X-T3 digital camera to an Apple 11″ MacBook Air computer, via a TetherTools USB cable. Fujifilm X Aquire (free) was used to save JPG files to a folder on the desktop of my MacBook Air; both JPG and RAF files were saved to one of two memory cards in the X-T3.

Apple “Preview” was used to view the JPG files saved to my MacBook Air. Looking at larger versions of the photos than can be seen on the X-T3 LCD enabled me to position the exuvia exactly as I wanted.

Notice the left eye is overexposed slightly (as well as the farthest tip of the left middle leg), probably caused by positioning the subject too close to the white background. Hey, it’s been a while since I did much studio macro photography — I need to play myself into game shape!

More details, including some of the tips and tricks I promised, will be provided in my regularly-scheduled blog post on Monday, 10 August 2020. Please stay tuned!

The Backstory

Swift River Cruiser dragonfly (Macromia illinoiensisexuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female.

Copyright © 2020 Walter Sanford. All rights reserved.

First foray into tethered shooting

August 5, 2020

My first foray into tethered shooting occurred on 01 August 2020. Although I felt like I had no idea what I was doing, I was able to successfully connect my Fujifilm X-T3 digital camera to an Apple 11″ MacBook Air computer, via a TetherTools USB cable. The screen on my laptop shows the display for the FUJIFILM Tether Shooting Plug-in PRO (Mac) for Adobe Lightroom.

Screen display for 11″ MacBook Air.

I will backfill this post with more details about the hardware and software used to capture the following image, taken a few days after “first light.” In the meantime, I’m SO LATE in publishing my blog post for Wednesday I just want to put something out there STAT. Please revisit this post at a later time to read the updated version.

A Swift River Cruiser dragonfly (Macromia illinoiensis) exuvia was collected on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. This individual is a female. Notice the prominent horn on the head, a key field mark for exuviae from Family Macromiidae (Cruisers).

Ignore the bad background and quick-and-dirty lighting — this photo isn’t so much about making a good macro photo as it is the process used to make it. More later…I promise!

Copyright © 2020 Walter Sanford. All rights reserved.

Acceptable uncertainty

July 27, 2020

A teneral damselfly was spotted by Michael Powell during a photowalk with me along a mid-size stream in Fairfax County, Virginia USA.

teneral: adult after it has just emerged, soft and not definitively colored. Source Credit: Glossary [of] Some Dragonfly Terms, by Dennis Paulson.

Teneral odonates, especially females, can be challenging at best to identify with certainty. And so it is with this one.

The first photo is the record shot. (Get a shot, any shot.) I think I might have just missed focus on the face.

No. 1 | 15 JUL 2020 | Fairfax County, VA | teneral damselfly

Refine the shot.

No. 2 | 15 JUL 2020 | Fairfax County, VA | teneral damselfly

Although this individual is definitely a member of Family Coenagrionidae (Narrow-winged Damselflies), both the genus/species and gender are somewhat uncertain.

It appears to be an Argia sp. based on long tibial spines. I think it is a male. Source Credit: Mike Boatwright, founder and administrator of the Virginia Odonata Facebook group.

For what it’s worth, Mike Powell and I saw three species of damselflies during our outing: Blue-tipped Dancer (Argia tibialis); Dusky Dancer (Argia translata); and Powdered Dancer (Argia moesta).

I’m not sure of the gender. I see what might be hamules, indicating this individual is male, but also see what looks like a female stylus (plural: styli) near the tip of the abdomen, indicating this might be a female.

Bonus Bugs and More

Look closely at Photo No. 1, the “record shot.” Notice the small orange colored insect perched along the bottom of the same rock on which the damselfly is perched. Can anyone identify Bonus Bug No. 1?

Post Update: “The fly at the [bottom] of this photo may be a black fly (Simuliidae).” Source Credit: John Smith, member “BugGuide” Facebook group.

Now look at Photo No. 2. Notice there is some type of dark insect that’s perched along the same edge of the rock as the damselfly. Can anyone identify Bonus Bug No. 2?

Post Update: “The bug at the bottom of your photo appears to be a caddisfly.” Source Credit: John Smith, member “BugGuide” Facebook group.

Also notice the dark insect is perched near what might be the exuvia from which the damselfly emerged, as shown in Photo No. 2. It’s tannish in coloration.

I didn’t see either the bonus bugs or possible exuvia when we were in the field. Of course!

Related Resource: Newly emerged damselflies, a companion blog post by Michael Powell.

Copyright © 2020 Walter Sanford. All rights reserved.

Sable Clubtail dragonfly (male, No. 2)

July 10, 2020

A Sable Clubtail dragonfly (Stenogomphurus rogersi) was spotted by Michael Powell during a photowalk at a location in Fairfax County, Virginia USA. This individual is a male, as indicated by his “indented” hind wings, and terminal appendages.

Look at the blade of grass on which the Sable is perched. Notice the “leftovers” from an afternoon snack eaten by the dragonfly before the photo was taken.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

Male dragonflies have three terminal appendages, collectively called “claspers,” that are used to grab and hold female dragonflies during mating: an upper pair of cerci (“superior appendages”); and a lower unpaired epiproct (“inferior appendage”). The epiproct for Sable Clubtail is essentially a wide plate with two prongs.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

The spiky green grass shown below is probably shallow sedge (Carex lurida) according to Drew Chaney, a.k.a., “Plant Man Drew.”

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

Field Observations

All of the photos in the preceding gallery show male No. 2 perched on vegetation overhanging a small stream, enabling him to both hunt/feed and wait for an opportunity to mate with a female.

Natural History: Males perch on sunlit vegetation overhanging stream or on flat rocks in shade at head of riffle, fly up into trees when disturbed. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 6102-6103). Princeton University Press. Kindle Edition.

In my experience, Sable Clubtails — both male and female — also perch on ground cover vegetation in sunny clearings near small streams. For example, see my recent blog post featuring male No. 1.

Sable does in fact fly up into trees when their “flight” response is triggered by overzealous photographers; they have been observed perched in trees as high as 20 feet above the ground. Be patient — usually they return to the ground soon afterward.

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

Sable Clubtail dragonfly (male, No. 1)

June 26, 2020

After a two-year hiatus since I spotted my first Sable Clubtail dragonfly (Stenogomphurus rogersi) during June 2018, it was a pleasure see an old friend again!

The first photo is the “record shot” for this individual, that is, “get a shot, any shot.” It is literally the first shot I took as soon as I spotted the Sable male. As you can see, he was looking in my direction so I was unable to sneak up on him. That proved to be problematic.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

I tried to move slowly into position for a lateral view of the dragonfly.

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

The last photo is almost as far as I moved before Mr. Sable flew away — five shots and it was game over, man!

13 JUN 2020 | Fairfax County, VA | Sable Clubtail (male)

Later the same day I  was fortunate to photograph a more cooperative male that will be featured in a follow-up post.

Rare to Uncommon

Sable Clubtail has a limited range and is classified as a rare to uncommon species of odonate. The following map shows all official records for Sable Clubtail in the United States of America.

DSA Distribution Viewer | Sable Clubtail

Source Credit: Abbott, J.C. 2006-2018. OdonataCentral: An online resource for the distribution and identification of Odonata. Available at http://www.odonatacentral.org. (Accessed: June 11, 2018).

Key: blue dots = Dot Map Project; green dots = Accepted records; yellow dots = Pending records.

As you would expect, there are few official records for the Commonwealth of Virginia, and fewer records for Northern Virginia.

The Backstory

A short segment of a small stream that flows through a park in Northern Virginia seems to provide ideal habitat for Sable. By the end of Summer 2018, the stream had been degraded significantly by siltation as a result of runoff from dirt that was dumped uphill from the stream.

The following year, the stream channel was almost completely choked by vegetation that I assume flourished in the nutrient-rich sediment that had flowed into the stream. Net result: One and only one Sable Clubtail dragonfly was observed by several spotters who visited the stream site during 2019.

That’s the bad news. The good news is I saw at least three Sable Clubtails when I visited the stream site on Saturday, 13 June 2020. That’s not as many individuals as I saw in 2018, but the species seems to have rebounded a little from the damage done to its habitat.

As Jeff Goldblum said in Jurassic Park, “Life finds a way.” Let’s hope!

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

Common Green Darner dragonfly (external female reproductive anatomy)

June 5, 2020

For some species of odonate exuviae, sex is indicated by a form of remnant reproductive anatomy. These external structures don’t look exactly the same for all species of dragonflies and damselflies, but their function is identical.

As far as I know, this is true for all species in the Family Aeshnidae (Darners) such as Common Green Darner dragonfly (Anax junius).

The following photograph shows a ventral view of a female Common Green Darner dragonfly. Notice the external reproductive anatomical structure on abdominal segment nine (S9) is virtually identical to the remnant anatomical structure on S9 of the exuvia, shown above.

Original photo used with permission from Louisa C. Craven.

The Backstory

My dear friend Louisa Craven discovered the lifeless adult dragonfly while on vacation with her family in Nags Head, North Carolina USA. Louisa is an accomplished wildlife photographer who developed an interest in odonates as a result of many photowalks with me.

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Macromiidae larvae/exuviae are horny

May 15, 2020

A prominent horn on the face is a key field mark for larvae/exuviae in the Family Macromiidae (Cruisers), as shown in the following photograph of a Swift River Cruiser dragonfly (Macromia illinoiensis) exuvia.

The base of the triangular horn is located above the labium (face mask), between the long, thin antennae.

The specimen was collected, with permission from park staff, on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA.

Tech Tips

The subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. The specimen was posed on its dorsal side, so the camera was focused on the face-head-ventral view of the exuvia. The image was rotated 180° during post-processing.

My vintage 2009 Apple iMac desktop computer is too old to support drivers for importing RAF files from my Fujifilm X-T3 mirrorless digital camera into either Apple Aperture or Adobe Lightroom.

The work-around is to use a free application from Fujifilm that converts RAF files to TIFF files, which can be opened and edited with Aperture and Lightroom. Problem is I’m a big procrastinator and haven’t learned how to use the file converter application, so I simply edited one of the JPGs straight from the camera.

For the most part, the finished image looks fairly good although the eyes are blown out a little to a lot. JPG files have less dynamic range than RAF files so I was unable to recover the blown highlights.

Hmmm, it might be time to buy a new desktop computer!

Post Updates

I finally got around to figuring out how to use the free Fujifilm application to convert RAF files to TIFFs. See my follow-up blog post entitled “RAW FILE CONVERTER EX 3.0” for step-by-step instructions.

10 photos (converted from RAF to TIFF), including the one-off featured in this blog post, were used to create a focus-stacked composite image of the specimen that is a little closer to what I had in mind when I set up the photo shoot.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Hylogomphus adelphus exuvia

April 29, 2020

An Anisoptera exuvia was collected by Freda van den Broek on 10 June 2019 along the St. Croix River in Polk County, Wisconsin USA.

This specimen is definitely a member of Family Gomphidae (Clubtails), probably Mustached Clubtail (Hylogomphus adelphus).

10 JUN 2019 | Polk County, WI | Anisoptera exuvia (face-head-dorsal)

Related Resources

Tech Tips

This subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. This photo is a “one-off,” that is, not a composite image.

Eight (8) photos of the specimen were taken using an aperture of f/16; in-camera focus peaking was used to highlight select areas in each photo. Adobe Photoshop CC 2017 will be used to create a focus-stacked composite image of the exuvia.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Too dark or too light?

April 27, 2020

The following Anisoptera exuvia — collected by Freda van den Broek on 10 June 2019 along the Red Cedar River in Barron County, Wisconsin USA — is definitely a member of Family Gomphidae (Clubtails), possibly Rusty Snaketail (Ophiogomphus rupinsulensis).

Dorsal-lateral view

Nine (9) photos of the specimen were taken using an aperture of f/16; in-camera focus peaking was used to highlight select areas in each photo. Adobe Photoshop CC 2017 was used to create the focus-stacked composite image shown below.

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (dorsallateral)

When I previewed the RAW files used to create the preceding composite image, I thought most of the files look too dark.

So I did a do-over using 15 photos, resulting in a new version of the composite that is perfectly in focus but a little too light. Compare/contrast the two composite images and you should notice it’s easier to see the mid-dorsal hooks along the abdomen in the first image. The primary purpose for the images is to illustrate those field marks, therefore I think the first (darker) image is better.

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (dorsallateral)

Face-head-dorsal view

Five (5) photos of the specimen were taken using an aperture of f/16; in-camera focus peaking was used to highlight select areas in each photo. Adobe Photoshop CC 2017 was used to create the focus-stacked composite image shown below.

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (face-head-dorsal)

My first impression of the version shown above is it’s too dark, and I second-guessed myself for not shooting more photos for the focus stack.

I created a new focus-stacked composite image using a little more light and 14 photos. When I examined the RAW files used to create the new composite image (shown below), I thought most of the files still look too dark. (But I was wrong.)

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (face-head-dorsal)

So I created a third version using much more light and 24 photos. Although it’s debatable which image looks best, the first- and second images show a few key field marks of the antennae better than the third image.

It turns out the antennae are one indicator this specimen is from the genus Ophiogomphus (Snaketails), so the first two (darker) images are the winners once again.

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (face-head-dorsal)

For what it’s worth, the second of three images is my favorite as indicated by the fact that the image is cropped so there’s room for annotations.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Clubtail exuvia (dorsal-lateral view)

April 24, 2020

The following Anisoptera exuvia — collected by Freda van den Broek on 10 June 2019 along the Red Cedar River in Barron County, Wisconsin USA — is definitely a member of Family Gomphidae (Clubtails), possibly Rusty Snaketail (Ophiogomphus rupinsulensis).

10 JUN 2019 | Barron County, WI | Anisoptera exuvia (dorsallateral)

Notice the exuvia has little stubby mid-dorsal hooks along the length of its abdomen, and lateral spines on abdominal segments seven through nine (S7-S9).

Tech Tips

This subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.

15 photos of the specimen were taken using an aperture of f/16; in-camera focus peaking was used to highlight select areas in each photo. Adobe Photoshop CC 2017 was used to create the focus-stacked composite image shown above.

Copyright © 2020 Walter Sanford. All rights reserved.


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