Posts Tagged ‘Family Macromiidae (Cruisers)’

Beware of look-alikes!

September 28, 2021

Some species of dragonfly larvae/exuviae look similar to other species. Here are a couple of look-alikes from two different families that might fool you.

One species of Corduliidae in our region [North America], Epitheca princeps, resembles the macromiid general body shape and is nearly as large, but the legs are short compared to its body dimensions and it lacks a triangular frontal projection. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 329.

The first annotated image shows a ventral view of a Prince Baskettail (Epitheca princeps) exuvia. E. princeps is a member of Family Corduliidae (Emeralds).

Notice the appearance of the E. princeps exuvia is quite similar to the Stream Cruiser (Didymops transversa) exuvia shown below. D. transversa is a member of Family Macromiidae (Cruisers).

The E. princeps exuvia features lateral spines and well-developed mid-dorsal hooks on some abdominal segments. Notably “it lacks a triangular frontal projection” (K. J. Tennessen), or stated more simply, there isn’t a “horn” on its face-head.

The D. transversa exuvia also features lateral spines and mid-dorsal hooks, as shown below. Notice the mid-dorsal hooks aren’t as cultriform as E. princeps. In contrast to the E. princeps exuvia, notice the prominent “horn” on the face of the D. transversa exuvia. It’s all about the “horn.”

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

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Copyright © 2021 Walter Sanford. All rights reserved.

Macromiidae – It’s all about the “horn.”

September 24, 2021

A “horn” on the face-head is a characteristic field mark for odonate larvae/exuviae in the Family Macromiidae (Cruisers).

Look closely at the full-size version of each of the following photos and you should be able to see the horn on the face of a Stream Cruiser dragonfly (Didymops transversa) exuvia that was collected during mid-April 2021.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (face-head)

It’s easier to see the horn in the next photo…

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

The horn is clearly visible in the last photo. Notice there are three “bumps” located between the eyes of the exuvia: the middle bump is the horn; the antennae bases are located to the left and right of the horn.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

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Copyright © 2021 Walter Sanford. All rights reserved.

Test shots: Didymops transversa exuvia

September 21, 2021

An exuvia from a Stream Cruiser dragonfly (Didymops transversa) was collected from one of the concrete abutments of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

I prefer to photograph odonate exuvia like this one “as is” — presumably its appearance is similar to the way larva looked when it lived underwater.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (dorsal)

If so, then I’m guessing D. transversa larvae are bottom dwellers, as indicated by the dirty, sediment-covered dorsal side and relatively clean ventral side of this specimen.

13 APR 2021 | PNC. William County, VA | Stream Cruiser exuvia (ventral)

Post Update

The nymphs are sprawlers that cling to roots or hunker down in sediments of mixed sand and silt particles. Source Credit: K. J. Tennessen, Dragonfly Nymphs of North America, https://doi.org/10.1007/978-3-319-97776-8_10, Macromiidae, p. 330.

The Backstory

The preceding photos were shot using the prototype for a homemade curved clear plastic tray intended for staging subjects against a white background.

With a few minor tweaks, the curved stage performed better than during initial testing. I needed to add a second external flash unit to more evenly illuminate the white background.

Although I’m fairly satisfied with the results of these test shots, more testing is required to be sure the set-up is working the way I want.

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Copyright © 2021 Walter Sanford. All rights reserved.

Stream Cruiser dragonfly (female)

May 18, 2021

A Stream Cruiser dragonfly (Didymops transversa) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This individual is a female, as indicated by her thick abdomen and terminal appendages.

13 MAY 2021 | Prince William County, VA | Stream Cruiser (female)

The female was perched in a large field near the same location where Mike Powell found a Stream Cruiser exuvia on 13 April 2021.

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Copyright © 2021 Walter Sanford. All rights reserved.

Exuvia from Family Macromiidae (Cruisers)

May 14, 2021

Michael Powell spotted a large odonate exuvia clinging to the concrete abutment of a man-made dam located along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This cast skin is definitely from a member of Family Macromiidae (Cruisers), as indicated by its long legs and the shape of its body.

13 APR 2021 | Prince William County, VA | Stream Cruiser (exuvia)

Mike’s macro photo of the same subject (shown below) turned out better than mine, taken with a superzoom bridge camera. Look closely at the full-size version of Mike’s photo. Nothing says Family Macromiidae (Cruisers) like the “horn” on the front of the face/head of the exuvia!

Photo used with written permission from Michael Powell.

The following excerpt from Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, shows the couplet that I think indicates this specimen is from a Stream Cruiser dragonfly (Didymops transversa).

The adult flight periods for the three species of cruisers found in Northern Virginia provide circumstantial evidence in support of my tentative identification. Source Credit: “Dragonflies of Northern Virginia” Web site by Kevin Munroe.

What’s next?

The specimen was collected in order to shoot a complete set of macro photographs of the exuvia in my home “studio.”

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Copyright © 2021 Walter Sanford. All rights reserved.

Swift River Cruiser exuvia (face-head)

November 20, 2020

The following image is a focus-stacked composite of three photos, focused on the left eye, right eye, and both eyes respectively.

27 May 2017 | Riverbend Park | Swift River Cruiser (exuvia, face-head)

Tech Tips

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

Several photos were taken using my Canon EOS 5D Mark II digital camera, a Kenko 12mm extension tube, and Laowa 25mm Ultra Macro Lens, set for f/4.0 (the sweet spot for this lens) at ~3.0x magnification.

Godox TT685C external flash was used to backlight the background (a piece of translucent white plastic) and a Godox TT685F external flash was used as a key light on the right side of the subject. The flash was triggered wirelessly by a Godox X2TC.

Check the EXIF/IPTC info for the photograph for complete details regarding photo gear and camera settings.

Adobe Photoshop CC 2017 was used to create a focus-stacked composite image that was edited using Apple Aperture.

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.

When is close too close?

October 14, 2020

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. The prominent horn on the head — a key field mark for exuviae from Family Macromiidae (Cruisers) — is noticeable in the following photo, although maybe not recognizable.

This photo is one of several test shots using “The Macroscope,” my nickname for the Laowa 25mm Ultra Macro Lens. The Laowa lens was mounted on my Canon 5D Mark II digital camera with a 12mm Kenko extension tube between the lens and camera body.

My new Laowa LED Ring Light was mounted on the front of the lens, powered by an Anker PowerCore+ 26800 PD 45W battery. The Laowa LED Ring Light was used to light the subject. A Sunpak LED-160 Video Light was used as a focusing aid. A Godox TT685C external flash was used to backlight a translucent white plastic background, using the “Meet Your Neighbours” technique. The flash was triggered wirelessly by a Godox X2TC.

The image is full-frame (5616 by 3744 pixels), that is, uncropped. The lens was set for f/4 (the “sweet spot” for the lens) at 4x magification. The camera was set for single point focus and spot metering, centered on the right eye of the exuvia.

Look closely at a full-size version of the image. At this magnification, the depth of field is very shallow: remnant ommatidia are clearly in focus; most of the image is out of focus.

In order to provide some context for what is shown in the first photo, the last photo shows the entire specimen. The photo gear used to take the shot is specified in a previous blog post.

When is close too close?

Close is too close when most of the subject is unrecognizable. At 4x magnification, it’s essential to use focus stacking to create a composite image.

The bigger take-away from this test shot is the Laowa LED Ring Light seems to work fairly well, albeit a sample size of one.

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Copyright © 2020 Walter Sanford. All rights reserved.

More experimentation with tethered shooting

August 12, 2020

Oh no! I have become the blogger who cried wolf. Yes, I’m guilty of over-promising and under-delivering. I promise to do better. Oops, I did it again! (Queue Britney Spears…)

Why tethered shooting?

In case you’re wondering what piqued my interest in tethered shooting, I was bored. I had figured out all there is to know about non-tethered shooting so I needed a new challenge. Not!

Tethered shooting enables me to quickly check composition, exposure, and focus, to name a few advantages of tethered versus non-tethered shooting — on a larger screen than the LCD on the back of my cameras.

Bear in mind, I don’t want to edit the photo files using my laptop computer (Apple 11″ MacBook Air) — I prefer to use my desktop computer (Apple 24″ iMac) for photo editing.

Latest testing

The following photos were taken by tethering my Fujifilm X-T3 digital camera to an Apple 11″ MacBook Air computer, via a TetherTools USB cable. FUJIFILM Tether Shooting Plug-in PRO was used to save JPG files to a folder on the desktop of my MacBook Air; in turn, the JPG images were displayed in Adobe Lightroom. Both JPG and RAF files were saved to one of two memory cards in the X-T3.

Notice the difference in way these two photos were lighted. Both shots were taken using a single off-camera flash. The position of the flash resulted in more- or less dramatic light. Each shot shows something better than the other, so I was unable to choose a clear favorite. What’s your preference?

Tips and Tricks

Oh yeah, the tips and tricks I have been promising are still in the pipeline. I made some screen grabs today to illustrate the process of tethered shooting. Turns out I overlooked a critical setting so all of the graphics are useless. Doh! Can you say “Do over”?

Copyright © 2020 Walter Sanford. All rights reserved.

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.


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