Archive for the ‘natural science’ Category

Pandora Sphinx moth

September 24, 2018

A Pandora Sphinx moth (Eumorpha pandorus) was spotted in the parking garage at The Beacon of Groveton, Fairfax County, Virginia USA.

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

The BugGuide Info page for Pandora Sphinx remarks that it is “An extra-spectacular sphinx moth.” I agree. One look at the full-size version of the preceding photo and I think you will too.

The Backstory

I noticed the moth when I entered the parking garage for the building where I live. The moth was perched on a cinder block wall, near a large security light. I was completely exhausted after a long day of photowalking at Huntley Meadows Park — my camera and external flash unit were in a backpack for camera gear and I was reluctant to unpack and set up to shoot photos of the moth. I took a second, longer look at the moth and knew it would be worth the effort. As it turns out, I was right — this is the best photo I shot all day, and one of my Top 10 Photos for 2018.

Editor’s Notes

Eumorpha pandorus is a new species for my life list of butterflies and moths. Sincere thanks to Sue and John Gregoire, Kestrel Haven Migration Observatory, for help in identifying this spectacular beauty.

Copyright © 2018 Walter Sanford. All rights reserved.

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Unicorn Clubtail (female terminal appendages)

September 22, 2018

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

Image used with permission from Bob Blakney.

Editor’s Notes

In my experience, female Unicorn Clubtail dragonflies are seen uncommonly. Sincere thanks to Bob Blakney for kindly granting permission to use his excellent photograph of this uncommon beauty for instructional purposes.

Bob’s photo was taken on 18 May 2012 at Occoquan Bay National Wildlife Refuge using a Canon EOS Rebel T2i digital camera and Tamron AF 18-270mm macro lens.

Copyright © 2018 Walter Sanford. All rights reserved.

Gray Petaltail (male terminal appendages)

September 20, 2018

“Bender,” my nickname for a male Gray Petaltail dragonfly (Tachopteryx thoreyi) with a malformed abdomen, is featured in the following set of annotated photos.

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

All 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”).

Gray Petaltail males have “indented” hind wings, as shown in the last photo.

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

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

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.

Life and death at Occoquan Bay revisited

September 16, 2018

I revisited the set of photos that I shot of an Osprey (Pandion haliaetus) with a fish in its talons, perched on a dead tree limb overhanging Fox Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia.

The Osprey was looking at me directly in the following photo. I wonder what the bird was thinking. With a piercing glare like that, I’m guessing he wasn’t thinking “Would you like to join me for lunch?”

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

In stark contrast with the Osprey’s piercing glare, notice the fish’s vacant stare.

Copyright © 2018 Walter Sanford. All rights reserved.

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.

More Wild Turkey at OBNWR

September 10, 2018

Several Wild Turkey (Meleagris gallopavo) were spotted during a photowalk along Fox Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

There were four birds in the group, foraging along the road. The red-headed individual is a male.

Copyright © 2018 Walter Sanford. All rights reserved.

Black Swallowtail butterfly

September 8, 2018

A Black Swallowtail butterfly (Papilio polyxenes) was spotted during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

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.


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