Archive for the ‘How To’ Category

Gray Petaltail (female terminal appendages)

September 18, 2018

For those species of dragonflies that do not display sexual dimorphism, males and females are nearly identical in appearance except for their terminal appendages. For example, male and female Gray Petaltail dragonflies (Tachopteryx thoreyi) are similar in appearance.

Two field markers can be used to identify female Gray Petaltails, as shown in the following annotated images: 1) they have two terminal appendages (cerci) rather than three (males); and 2) their hind wings are rounded rather than “indented” (males).

30 MAY 2018 | Northern Virginia | Gray Petaltail (female)

Female dragonflies have a pair of cerci (superior appendages) that have little or no function.

30 MAY 2018 | Northern Virginia | Gray Petaltail (female)

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

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Helocordulia uhleri exuvia

September 14, 2018

An odonate exuvia from the Family Corduliidae (Emeralds) was collected on 06 April 2018 by Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group.

The Backstory

I found a recently-emerged teneral sundragon still clinging to its exuvia along Beck Creek in Amherst County, Virginia USA. Source Credit: Michael Boatwright.

Image used with permission from Michael Boatwright.

After snapping a photo, I gently moved the teneral adult to a nearby blade of grass, snapped another shot, and then collected the exuvia. Although I have seen both Selys’ Sundragon (Helocordulia selysii) and Uhler’s Sundragon (Helocordulia uhleri) in that area, I assumed this one was Selys’ since it’s the more common species there. Source Credit: Michael Boatwright.

Image used with permission from Michael Boatwright.

This is a small genus [Helocordulia] of only two known species found in only the eastern United States and Canada. Source Credit: Needham, J.G., M.J. Westfall, and M.L. May. March 2014. Dragonflies of North America, 3rd Edition: p. 376. Scientific Publishers, Gainesville, Florida.

A two-step process was used to verify the genus and species of the exuvia.

  1. Determine the family.
  2. Determine the genus and species.

Step 1. Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06). Here’s the decision tree used to identify the exuvia as a member of the Family Corduliidae (Emeralds).

  • The specimen has a mask-like labium (prementum) that covers the face, as shown in Image No. 1, characteristic of four families of odonates: Cordulegastridae (Spiketails); Corduliidae (Emeralds); Libellulidae (Skimmers); and Macromiidae (Cruisers).
  • There is no horn on the face-head, characteristic of Macromiidae, so it’s not a cruiser.
  • Cordulegastridae has jagged crenulations on its labium, so it’s not a spiketail. The crenulations for Corduliidae and Libellulidae look similar.
  • Look at the anal pyramid to differentiate Corduliidae and Libellulidae: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts. [Editor’s Note: It’s probably Libellulidae if the cerci are less than half the length of the paraprocts.]

In summary, the exuvia has a mask-like labium with relatively smooth crenulations, and no horn on its face-head. Although the specimen is too dirty to see the anal pyramid clearly, field observation of the teneral adult confirms the dragonfly is a member of Genus Heliocordulia (Sundragons) in the Family Corduliidae (Emeralds).

Image No. 1 shows a face-head view of the exuvia, magnified approximately three times life size (~3x). Notice the labium that covers the face is missing one of two palpal lobes; the missing lobe is shown in Image No. 4.

No. 1 | Helocordulia uhleri | exuvia (face-head)

Step 2. Genus and species

The dichotomous key for “Helocordulia larvae” that appears on p. 377 in Dragonflies of North America (Needham, et al.) was used to verify the genus and species of the exuvia. Markers that match this specimen are highlighted in boldface green text. Three boldface green asterisks (***) are used to highlight the thread for identification of this specimen.

***1. Dorsal hooks on abdominal segments 7-9; palpal setae 7; lateral spines of segment 8 about 1/2 as long as on segment 9 [uhleri]
1’. Dorsal hooks on abdominal segments 6-9; palpal setae usually 6; lateral spines of segment 8 about as long as on segment 9 [selysii]

Image No. 2 shows a dorsal view of the specimen. Notice the mid-dorsal hooks on abdominal segments seven through nine (S7-9), labeled using white text.

No. 2 | Helocordulia uhleri | exuvia (dorsal)

Image No. 3 clearly shows the dorsal hooks on abdominal segments seven through nine (S7-9). This distinctive character confirms the identity of the species as H. uhleri.

No. 3 | Helocordulia uhleri | exuvia (lateral)

Image No. 4 shows a palpal lobe from the specimen, viewed from the inside, magnified approximately three times life size (~3x). There is one palpal seta and at least seven sites where setae might have been located before the palpal lobe broke off the prementum. Although this character is inconclusive for confirming the species (given the condition of the palpal lobe), it’s not exclusive.

No. 4 | Helocordulia uhleri | palpal lobe (inside)

Image No. 5 shows a ventral view of the specimen. Notice the lateral spine on abdominal segment eight (S8) is about half as long as the lateral spine on segment nine (S9).

When measuring spines, I measure them ventral from the inside corner to the tip. There is a suture on the ventral side, near the base, that makes a nice repeatable starting point for measuring. Source Credit: Ken Tennessen, personal communication.

No. 5 | Helocordulia uhleri | exuvia (ventral)

Takeaways

Perhaps the biggest takeaway from working to identify this exuvia is the fact that it enabled the correct identification of the teneral adult dragonfly that Mike observed and photographed. In fact, Mike is the one who first recognized the species is H. uhleri, based upon the number of mid-dorsal hooks on the exuvia.

Tech Tips

Mike Boatwright’s photographs, taken in-situ, were shot using a Canon EOS 7D digital camera and Canon 300mm prime lens paired with a Canon 1.4x Extender EF.

The following equipment was used to shoot Image No. 2, 3, and 5: 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); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode. Image No. 1 and 4Canon MP-E 65mm Macro lens (manual focus only, set for ~3x magnification) plus the multiple-flash setup.

Image No. 1-5 are focus-stacked composite images created and annotated using Adobe Photoshop CC 2017: Image No. 1 (seven photos); Image No. 2 (30 photos); Image No. 3 (16 photos); Image No. 4 (10 photos); Image No. 5 (24 photos).

Copyright © 2018 Walter Sanford. All rights reserved.

Studio macro photography rig

September 12, 2018

This blog post features a couple of quick-and-dirty photos that provide a behind-the-scenes look at some of the photography gear I use for studio macro photography.

The following equipment is shown in the first photo, taken using an iPad mini (with retina display): 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); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode.

The Canon DSLR is mounted on a Neewer Pro 4-Way Macro Focusing Rail Slider using a Manfrotto quick-release plate. Although the quick-release plate isn’t essential gear, it makes set-up and tear-down easy and fast. The focusing rails are mounted on a Manfrotto 405 Pro Digital Geared Head, connected to a Manfrotto 055XPROB Pro Tripod [discontinued].

Photography gear used for studio macro photography.

A Canon 580EX II Speedlite is mounted on a Manfrotto 054 Magnesium Ball Head with Q2 Quick Release [discontinued], connected to a Vanguard Alta Pro 263AB 100 Aluminum Alloy Tripod. A Canon 580EX Speedlite is mounted on a Sunpak 8001 UT medium duty aluminum tripod.

The last photo, taken using a Panansonic Lumix DMC-FZ150 superzoom bridge camera, shows the “stage” used for posing subjects such as the Zebra Clubtail dragonfly (Stylurus scudderi) exuvia shown in the preceding photo. A Tether Tools “Rock Solid Master Articulating Arm & Clamp Kit” connects one end of the articulating arm to a leg of the Manfrotto tripod; a Manfrotto 2909 Super Clamp is connected to the other end of the articulating arm and used to hold a piece of opaque white plastic that is 12″ square. (Yep, that’s a folded paper towel used to prevent the clamp from scratching the plastic.) The plastic has a smooth side and a textured side; I prefer the textured side. An Opteka Triple Axis Spirit Level is used to level the “stage.”

Macro photography “stage.”

Product Reviews

See “Good news, bad news,” a related blog post in which I reviewed the Manfrotto 405 geared tripod head and Neewer focus rails.

Manfrotto makes an articulating arm that is similar to the one made by Tether Tools, shown above. The Manfrotto 244N Variable Friction Magic Arm is more expensive than the Tether Tools “Rock Solid Master Articulating Arm,” so I chose the less expensive arm. I’m reminded of the old saying “you get what you pay for.” In retrospect, I don’t recommend any of the articulating arms and clamps made by Tether Tools.

Copyright © 2018 Walter Sanford. All rights reserved.

Epitheca princeps exuvia

September 6, 2018

An odonate exuvia was collected by Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, on 07 June 2018 at Otter Lake in Amherst County, Virginia USA.

A two-step process was used to identify the genus and species of the specimen.

  1. Determine the family.
  2. Determine the genus and species.

Step 1. Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06). Here’s the decision tree used to identify the exuvia as a member of the Family Corduliidae (Emeralds).

  • The specimen has a mask-like labium (prementum) that covers the face, as shown in Image No. 1, characteristic of four families of odonates: Cordulegastridae (Spiketails); Corduliidae (Emeralds); Libellulidae (Skimmers); and Macromiidae (Cruisers).
  • There is no horn on the face-head, characteristic of Macromiidae, so it’s not a cruiser.
  • Cordulegastridae has jagged crenulations on its labium, so it’s not a spiketail. The crenulations for Corduliidae and Libellulidae look similar.
  • Look at the anal pyramid to differentiate Corduliidae and Libellulidae: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts, as shown in Image No. 4. [Editor’s Note: It’s probably Libellulidae if the cerci are less than half the length of the paraprocts.]

In summary, the exuvia has a mask-like labium with relatively smooth crenulations, no horn on its face-head, and the cerci are more than half as long as the paraprocts, confirming that the specimen is a member of Family Corduliidae (Emeralds).

No. 1Epitheca princeps | exuvia (face-head)

Step 2. Genus and species

Characters from two dichotomous keys were used to identify the genus and species: Prince Baskettail dragonfly (Epitheca princeps). See Epitheca princeps exuvia, another of my illustrated guides to identification of odonate exuviae, for a detailed explanation of the decision tree used to identify the genus and species of this specimen.

No. 2 | Epitheca princeps | exuvia (dorsal)

This individual is a male, as indicated by the vestigial hamuli visible on the ventral side of abdominal segments two and three (S2-3).

No. 3Epitheca princeps | exuvia (ventral)

Notice the cerci are at least half as long as the paraprocts, as shown in Image No. 4.

No. 4Epitheca princeps | exuvia (posterior abdomen)

Image No. 5 shows a dorsal-lateral view of the mid-dorsal hooks.

No. 5Epitheca princeps | exuvia (dorsal-lateral)

Look-alike species

I really wanted this specimen to be Stream Cruiser dragonfly (Didymops transversa). I think exuviae from D. transversa and E. princeps are similar in appearance — an opinion not shared by at least one expert on identification of odonate exuviae.

Two characters proved to be the deal-breaker that forced me to abandon D. tranversa in favor of E. princeps. 1) The specimen does not have a horn on its face-head. 2) This specimen is only 25 mm long (2.5 cm); D. transversa larvae/exuviae are 30 mm long (3.0 cm), according to Dragonflies of North America, Needham, James G., et al.

Tech Tips

The following equipment was used to shoot Image No. 1-5: 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); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode.

Image No. 1-5 are focus-stacked composite images created and annotated using Adobe Photoshop CC 2017: Image No. 1 (7 photos); Image No. 2 (22 photos); Image No. 3 (19 photos); Image No. 4 (10 photos); Image No. 5 (20 photos).

Copyright © 2018 Walter Sanford. All rights reserved.

Stylurus sp. exuvia

August 25, 2018

Two similar odonate exuviae were collected by Michael Boatwright on 11- and 13 July 2018 along a medium-size stream in Amherst County, Virginia USA. Mike and I collaborated to identify the specimen collected on 13 July.

A two-step process was used to identify the genus and species of the exuvia.

  1. Determine the family.
  2. Determine the genus and species.

Step 1. Family

First, determine the family of the specimen. For reference, watch the excellent Vimeo video, Identifying dragonfly larva to family (8:06). Here’s the decision tree used to identify the exuvia as a member of the Family Gomphidae (Clubtails).

  • The specimen has a flat labium (prementum) that doesn’t cover the face (not mask-like), as shown in Image No. 1, 3-5.
  • Antennae are club-like (not thin and thread-like, as in Aeshnidae larvae), as shown in Image No. 1.
  • Eyes not exceptionally large compared to the size of the head (not large, as in Aeshnidae), as shown in Image No. 1.

It’s relatively simple and straightforward to recognize this specimen is a clubtail. Determination of the genus and species is more challenging.

No. 1 | Stylurus sp. | exuvia (face-head)

Step 2. Genus and species

Several dichotomous keys were used to determine the genus and species of the exuvia. (See Related Resources.) By far the easiest keys to use are found in Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz. Markers that match this specimen are highlighted in boldface green text. Three boldface green asterisks (***) are used to highlight the thread for identification of this specimen.

p. 7 – Key to the Genera of the Family Gomphidae

p. 9
***8a. Tibial burrowing hooks vestigial or lacking; 1-4 palpal teeth [see Image No. 5]; abdomen slender, no wider than head [see Image No. 2]. [Stylurus]

p. 16
[diagrams (showing palpal lobe)] … traced from Walker (1928)

This specimen is a species from the genus Stylurus, confirmed by Kenneth J. Tennessen, Ph.D. in Entomology (personal communication).

p. 17 – Key to the Species of the Genus Stylurus

***1b. Abdominal segment 9 less than twice as long as wide at base [see Image No. 2]. [2]

2a. Vestigial dorsal hook, represented on segment 9 by small flattened triangular rearward projection on mid-dorsal line, not hooklike in form. [3]
***2b. Nothing representing a hook on 9. [4]

3a. … [notatus] ← Elusive Clubtail
3b. … [plagiatus] ← Russet-tipped Clubtail

4a. Total length less than 34 mm; median lobe of labium very convex. [amnicola] ← Riverine Clubtail
***4b. Total length more than 34 mm [see Image No. 2]; median lobe of labium only slightly convex [see Image No. 5]. [scudderi] ← Zebra Clubtail

Note: See Walker (1928) for a complete description of the nymphs of Stylurus.

[diagrams (showing posterior abdomen)] … traced from Walker (1928)

The exuvia is ~37 mm (~3.7 cm) long, measured from end-to-end, including the antennae that extend ~1-2 mm in front of the face. The overall shape of the posterior abdomen most closely matches S. scudderi, as shown by tracings in the Soltesz key. The length of abdominal segment nine (S9) is less than its basal width. S9 is only slightly longer than S8. S10 is wider than its length.

No. 2 | Stylurus sp. | exuvia (dorsal)

Notice the flat labium (prementum) doesn’t cover the face of the specimen, as shown in Image No. 1, 3-5. The basal width of the lateral spine on abdominal segment nine (S9) in lateral view is approximately equal to the basal width of the spine in dorsal view.

No. 3 | Stylurus sp. | exuvia (lateral)

The lateral spine on abdominal segment nine (S9) is nearly as long as abdominal segment 10 (S10).

No. 4 | Stylurus sp. | exuvia (ventral)

The overall shape of the palpal lobes most closely matches S. scudderi, as shown by tracings in the Soltesz key. Note the median lobe of the labium (prementum) is only slightly convex, as shown by both the tracings and Image No. 5.

No. 5 | Stylurus sp. | exuvia (prementum)

What it is

According to the identification key for the genus Stylurus compiled by Ken Soltesz, this specimen is Zebra Clubtail (Stylurus scudderi).

Soltesz’s key is based, in part, on the excellent work of E. M. Walker in 1928. (See Related Resources.) Neither Walker’s paper nor Soltesz’s identification key includes Laura’s Clubtail (Stylurus laurae), described in 1932 (Benjamin Coulter, personal communication). There is considerable overlap in the characters used to identify S. laurae and S. scudderi that cannot be ignored.

We referred to two more identification keys, one of which is known to contain misinformation in the keys for S. laurae and S. scudderi (Kenneth J. Tennessen, personal communication) — if one is flawed, then so is the other since both keys refer to many of the same characters. That being said, the greatest number of matching characters indicates S. scudderi although S. laurae cannot be 100% ruled out.

Further evidence

One of the two virtually identical odonate exuviae that Mike Boatwright collected included a teneral adult that failed to emerge successfully.

After careful examination, Mike tentatively identified the adult as a male Zebra Clubtail (Stylurus scudderi) based on the following characteristics.

Face yellow with crossbars forming a dark “X” with a light center. Front half of frons yellowish; rear of frons and vertex dark. Top of thorax dark brown with two vertical yellowish white stripes, and a light colored mid-dorsal stripe narrowing to a point at the yellowish-white collar stripe. Humeral and anti-humeral stripes (T1 and T2) dark brown and almost completely fused. Area between T2 and T3 a fairly broad yellow stripe. T3 and T4 dark brown, mostly fused, and bordered by light colored broad oval area below.

Abdomen slender with dark blackish-brown segments. Two pale yellow spots on the sides of S2 with one completely covering the auricle. Anterior end of S3-6 and posterior end of S9 with thin pale yellow to whitish ring. Lateral edges of S7-9 widely expanding forming a club with broad irregular whitish-yellow markings on lateral surfaces. Source Credit: Michael Boatwright.

Significance

Either Zebra Clubtail (S. scudderi) or Laura’s Clubtail (S. laurae) are new species of odonates for Amherst County, Virginia USA, as shown by the Dragonfly Society of the Americas species checklist for Amherst County.

Zebra Clubtail is not within range of Amherst County; Mike’s discovery could indicate expansion of its range farther eastward into Virginia. Laura’s Clubtail is within range of Amherst County, although unknown to occur there.

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, a zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for Zebra Clubtail is 13 July to 02 October; Laura’s Clubtail is 20 June to 26 September.

Related Resources

Tech Tips

The following equipment was used to shoot Image No. 1-4: 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); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode. Image No. 5Canon MP-E 65mm Macro lens (manual focus only, set for ~2x magnification) plus the multiple-flash setup.

Image No. 1-5 are focus-stacked composite images created and annotated using Adobe Photoshop CC 2017: Image No. 1 (13 photos); Image No. 2 (14 photos); Image No. 3 (11 photos); Image No. 4 (18 photos); Image No. 5 (six photos).

Mike Boatwright’s photos, taken soon after the specimens were collected, were shot using a Samsung Model SM-G950U cell phone.

Copyright © 2018 Walter Sanford. All rights reserved.

Stylurus sp. exuvia, ongoing work

August 17, 2018

The work to identify an unknown species of odonate exuvia continues. More focus-stacked composite images are in the pipeline to be published in one or more follow-up blog posts.

13 JUL 2018 | Amherst County, VA | Stylurus sp. exuvia (dorsal view)

Tech Tips

The preceding image is a composite of 21 photos taken using the following equipment: 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); 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.

Related Resource: Stylurus sp. exuvia

Copyright © 2018 Walter Sanford. All rights reserved.

Stylurus sp. exuvia

August 15, 2018

The following image is a composite of 18 photos taken using the following equipment: 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); 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.

13 JUL 2018 | Amherst County, VA | Stylurus sp. exuvia (ventral view)

The Backstory

I am collaborating with my good friend Mike Boatwright, administrator of the Virginia Odonata Facebook group, to identify an odonate exuvia that he collected on 13 July 2018 in Amherst County, Virginia USA. We know the exuvia is from the Family Gomphidae (Clubtails) and are fairly certain it is a species from the genus Stylurus. At this point, several species are still in play.

Sincere thanks to Benjamin Coulter for providing guidance and related resources as Mike and I work through several dichotomous keys for identification of Stylurus larvae.

Look for one or more follow-up blog posts as the work progresses.

Related Resource: Stylurus sp. exuvia, ongoing work

Copyright © 2018 Walter Sanford. All rights reserved.

Habitat for Tiger Spiketail dragonfly

August 9, 2018

In the world of odonates, there are habitat generalists and habitat specialists. Tiger Spiketail dragonfly (Cordulegaster erronea) is a habitat specialist.

Habitat: Small forest streams and seeps, often with skunk cabbage and interrupted fern. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 7028-7029). Princeton University Press. Kindle Edition.

The following video shows ideal habitat for C. erronea: A clean, seep-fed small stream in the forest.

The black rock in the middle of the creek is approximately five feet (~5′) from the place in the stream channel where I was sitting on a Coleman camp stool. The video begins with me looking at a seep that feeds the stream; then I pan left, right, and back to center stage.

Tech Tips: The preceding movie looks better viewed in full-screen mode. The video was recorded in 1080p at 60 fps using a head-mounted GoPro Hero4 Black action camera. The camera was positioned so that it recorded what I saw when looking straight ahead; the scene changed by moving my head. 60 fps was used so that I could edit the video to show smooth slow-motion video of Tiger Spiketail dragonflies in flight. I think one of the bigger take-aways is a Tiger fly-by would have been recorded clearly enough to be able to identify the species. For what it’s worth, the closest focusing distance of the GoPro Hero4 Black is approximately 12 inches (~1′).

GoPro CapCam©

A GoPro QuickClip was used to mount an action camera on the bill of a baseball cap.

GoPro Hero4 Black action camera, plus QuickClip mount.

The GoPro Head Strap + QuickClip is compatible with all GoPro cameras and sells for $19.95 retail.

GoPro Hero4 Black action camera, plus QuickClip mount.

The Backstory

I visited the location shown in the video three times: Several Tiger Spiketail dragonflies were observed at the site on 19- and 26 July 2018; no Tiger Spiketails were spotted on 06 August 2018, the day the video was recorded. It’s worth noting that the adult flight period for C. erronea peaks in July in Northern Virginia (USA). Most of the window of opportunity was missed due to near record setting rainfall for the month of July, including a period of seven consecutive days of rain totaling nearly 10 inches!

Although I saw several Tiger Spiketail dragonflies, every individual was in flight and I was unable to shoot still photos and/or video — they were gone by the time I reached for my camera! The GoPro CapCam© is my solution to this problem.

An Apple iPad mini is used to remotely control the action camera using the GoPro app (formerly known as “Capture”) via Bluetooth. Among many features, the app provides real-time display of the camera field of view. The camera is positioned correctly on the bill of my cap by holding the iPad directly in my line of sight and adjusting the camera mount so the iPad is shown in the middle of the screen, against the background.

Copyright © 2018 Walter Sanford. All rights reserved.

“Bender” on grass

June 22, 2018

Gray Petaltail dragonfly (Tachopteryx thoreyi) is well-known for its tendency to perch on gray and tan colored surfaces, including tree trunks. Less well-known is the fact that Gray Petaltail perches wherever it wants, including tall grasses growing in the forested seeps from which the species emerges.

“Bender,” my nickname for a male Gray Petaltail with a malformed abdomen, is shown perched on grass stems in the following photo set.

No. 1 | 06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

The next photo provides a good view of the gentle curve in Bender’s abdomen, as well as his hamules, visible on the ventral side of abdominal segments two and three (S2 and S3).

No. 2 | 06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

Like many male odonates, Bender probably perched on the grass in order to make himself available for hook-ups with females of the same species.

No. 3 | 06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

Bender aggressively defended the prominent perch against other odonates that intruded upon his territory.

No. 4 | 06 JUN 2018 | Northern Virginia | Gray Petaltail (male)

No flash/flash

Compare/contrast Photo No. 3-4. The batteries in my external flash unit were almost drained completely by the time I shot the photos. As a result, the flash worked sometimes and didn’t work other times. I’m fairly certain the flash didn’t fire for the Photo No. 3, and equally certain it fired for Photo No. 4. Some photographers might contend the no-flash photo is “arty”; I contend Photo No. 4 — the fill-flash version — has better color balance, color saturation, and more detail in the shadows.

Copyright © 2018 Walter Sanford. All rights reserved.

Swift River Cruiser exuvia

April 25, 2018

A late-stage emergent teneral female Swift River Cruiser dragonfly (Macromia illinoiensis) was spotted on 27 May 2017 along the Potomac River at Riverbend Park in Fairfax County, Virginia USA. The exuvia was collected, with permission from park staff, after the female flew away from the place where she metamorphosed from a nymph to an adult.

No. 1 | 27 MAY 2017 | Riverbend Park | Swift River Cruiser (female)

The next image is a composite of 35 photos. The specimen is perfectly in focus from head-to-tail, including the legs.

The last image is a composite of eight photos. The focus point for each photo in the set is limited to the body only. Surprisingly, all six legs are acceptably in focus except for the tip of the left hind leg.

The official early-date for Swift River Cruiser dragonfly is 08 May in the Commonwealth of Virginia. Since the early-date for Royal River Cruiser dragonfly (Macromia taeniolata) is 15 May, the exuvia helps to confirm the identity of the adult is Swift River Cruiser. 10 October is the late-date for both species.

Tech Tips

Photo No. 1 was taken using my Panasonic Lumix DMC-FZ150 superzoom bridge camera plus Canon 580EX Speedlite, my go-to kit for photowalking.

The following equipment was used to shoot Photo No. 2 and 3: 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); Canon MT-26EX-RT Macro Twin Lite set for “Master” mode, and Canon 580 EX- and Canon 580EX II Speedlites set for “Slave” mode.

Photo No. 2-3 are focus-stacked composite images created using Adobe Photoshop CC 2017.

Related Resource: Swift River Cruiser (emergent female).

Copyright © 2018 Walter Sanford. All rights reserved.


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