Archive for the ‘damselflies’ Category

Ebony Jewelwing damselfly (male)

June 18, 2018

Look for Ebony Jewelwing damselflies (Calopteryx maculata) beginning in late-May/early-June along almost any small- to mid-size forested stream in Northern Virginia (USA).

This individual is a male, as indicated by the all-black coloration of his wings and by his terminal appendages.

Ebony Jewelwing is a member of Family Calopterygidae (Broad-winged Damselflies). American Rubyspot (Hetaerina americana) is the only other species of Broad-winged Damselfly found in Northern Virginia.

Related Resource: The adult flight period for Ebony Jewelwing is from April 27 to October 06, 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.

Copyright © 2018 Walter Sanford. All rights reserved.

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Another focus stacking face-off

April 19, 2018

Here’s another face-off between a single macro photo and a focus-stacked composite image. Let’s start with the composite image this time.

The first example is a composite image created from 14 photos.

In a recent blog post, I wrote…

My goal is to shoot the fewest number of photos (using a relatively small aperture such as f/18) that will show the entire specimen in focus when the photo set is focus-stacked to create a composite image. Source Credit: More Calico Pennant exuvia composite images.

I used to shoot several photos of a single focus point, e.g., the prementum, and select the sharpest image for editing/focus stacking. Now I’m using a wider aperture such as either f/11 or f/8 (for sharpness), shooting more photos, and using every photo that I take. My rationale is simple: A single photo may not be the sharpest photo of a single focus point, but it probably shows other areas that are in focus. In this case, I think more “raw material” is better than less.

The last example is one of the better photos from the set of 14. 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 following 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.

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.

Hetaerina americana exuvia

March 18, 2018

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.

Pattern recognition can be used to tentatively identify damselfly larvae/exuviae to the family level: the shape of the prementum is characteristic for each of the three families of damselflies that occur in the mid-Atlantic region of the United States of America; mnemonics can be used to remember each distinctive shape.

Family Calopterygidae (Broad-winged Damselflies) features a prementum with a shape that looks somewhat similar to Family Coenagrionidae (Narrow-winged Damselflies). Look for an embedded raindrop shape, located toward the upper-center of the prementum.

Also notice another marker for Calopterygidae: the first antenna segment is equal to or longer than the length of the other six (6) segments added together. (Editor’s Note: Some of the smaller antennae segments are missing. It’s likely those delicate parts broke off during shipping and/or cleaning.)

No. 2 | Hetaerina americana | exuvia (ventral)

Two markers verify the genus and species of this specimen as Hetaerina americana: the labial cleft extends only to the base of the palpal lobes, as shown in Photo No. 1; and the external gills are 8.5 mm to 10 mm long (Daigle, 1991), as shown in Photo No. 2.

Before and after

Photo No. 3 shows a dorsal view of the exuvia before it was cleaned in order to remove unknown fibers covering the body and dirt/debris that obscured the labial cleft in the prementum.

No. 3 | Hetaerina americana | exuvia (dorsal)

Photo No. 1, 2 and 4 show the exuvia after cleaning. The operation appears to have been successful, other than collateral damage to two legs.

No. 4 | Hetaerina americana | exuvia (dorsal)

The next photograph shows the damselfly during emergence from one of Bob Perkins‘ holding tanks. Good timing, Bob!

Image used with permission from Bob Perkins.

The last photo shows the adult American Rubyspot damselfly sometime after emergence. Hetaerina americana is 38-46 mm in total length (Paulson, 2011). This individual is a male, as indicated by its hamules and terminal appendages.

Image used with permission from Bob Perkins.

Related Resource: Florida Damselflies (Zygoptera) – A Species Key to the Aquatic Larval Stages, by Jerrell James Daigle. Technical Series, Volume 11, Number 1, December 1991. State of Florida, Department of Environmental Regulation.

Tech Tips

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

Adobe Photoshop CC 2017 was used to annotate selected images.

Bob Perkins’ photos were shot using a Canon EOS Rebel T3i camera body and Canon EF-S 60mm macro lens.

Copyright © 2018 Walter Sanford. All rights reserved.

American Rubyspot damselfly exuvia

March 12, 2018

An American Rubyspot damselfly (Hetaerina americana) nymph 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.

This individual is a member of the Family Calopterygidae (Broad-winged Damselflies), as indicated by the length of antenna segment 1 (shown below). See Hetaerina americana exuvia for a more detailed explanation.

No. 1 | Hetaerina americana | exuvia (dorsal)

If you look closely at the full-size version of both photos, then you should notice the specimen is covered by a lot of fibers of unknown origin.

That nymph was in the final instar when I collected it. Therefore it didn’t shed the algae and debris that had collected on its bristles. Source Credit: Personal communication with Bob Perkins.

A quick look at the prementum (below) shows the labial cleft, a key field marker for verifying the species, is obscured by some of the “debris” that Bob mentioned. As of this writing, the exuvia is soaking in a soapy water bath in the hope that it can be cleaned sufficiently to see that marker clearly.

No. 2 | Hetaerina americana | exuvia (ventral)

To be continued

Tech Tips

The following equipment was used to shoot Photo No. 1 and 2: 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.

Two Sunpak LED-160 Video Lights (each with a white translucent plastic filter) were used for both photos.

Adobe Photoshop CC 2017 was used to annotate both images.

Copyright © 2018 Walter Sanford. All rights reserved.

Before and after

March 6, 2018

A recent blog post entitled Getting Started features photos of four odonate exuviae collected by Michael Powell during a photowalk along the Potomac River in Fairfax County, Virginia USA.

Before

The first photograph is one of several quick-and-dirty shots I took of one of the exuviae, without removing it from the small plastic tub in which it is stored. As you can see, the specimen appears to be in poor condition. Well, appearance can be deceiving, as they say.

No. 1 | Potomac River, Fairfax County, VA | Zygoptera exuvia

After

The last photograph shows the same exuvia after soaking in a bath of soapy water for at least 24 hours. When the specimen was pliable, it could be re-posed and allowed to dry/harden for another 24 hours.

No. 2 | Potomac River, Fairfax County, VA | Zygoptera exuvia

The exuvia is missing a set wing pads and the abdomen is still dented/twisted. That being said, most people would agree the specimen looks much better. More importantly, it’s easier to see the anatomy of the exuvia.

Taxonomic classification

This individual is a member of the Family Coenagrionidae (Narrow-winged Damselflies) as indicated by its keystone-shaped prementum, shown in Photo No. 1. The next challenge is to identify its genus and species.

Copyright © 2018 Walter Sanford. All rights reserved.

Stylurus plagiatus exuvia

March 2, 2018

Michael Powell collected several odonate exuviae during a photowalk along the Potomac River in Fairfax County, Virginia USA, including two damselflies and two dragonflies. The exact date is uncertain, although Mike thinks the exuviae were collected sometime between 19-23 July 2017.

Both dragonfly exuviae are from the Family Gomphidae (Clubtails), as indicated by a flat labium that doesn’t cover the face as well as club-like antennae. The smaller specimen was identified as an Erpetogomphus designatus exuvia; this post describes the decision tree used to identify the larger specimen.

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

Refer to Photo No. 2, 3, and 4. Notice that abdominal segment nine (S9) is elongated, strongly suggesting this individual is a member of the genus Stylurus.

The dichotomous key for Stylurus larvae that appears on pp. 310-312 in Dragonflies of North America, Third Edition by Needham et al. was used to identify the species of the exuvia. The ninth couplet [9, 9′] is as follows.

9(7’). Length of abdominal segment 9 at least equal to its basal width; lateral spines of abdominal segment 9 at least 1-1/2 times as long as those of segment 8; dorsal hook of segment 9 often large, in southern specimens overhanging segment 10; each labial palp with 3 teeth in addition to end hook; greatest width of prementum at least 4/5 its length. [plagiatus]
9’. Length of abdominal segment 9 less than its basal width; lateral spines of abdominal segment 9 no more than 1-1/2 times as long as those of segment 8; dorsal hook of segment 9 small, sometimes vestigial; labial palp with 2-3 teeth in addition to end hook; greatest width of prementum no more than 3/4 its length. [10]

Abdominal segment nine (S9) is slightly longer than its basal width, as shown in Photo No. 2. The lateral spines of segment nine (S9) are much longer than segment eight (S8).

No. 2 | Stylurus plagiatus | exuvia (dorsal)

Photo No. 3 shows a dorsal view of the distal abdomen. Notice the large dorsal hook of abdominal segment nine (S9) overhangs segment 10 (S10), a key marker for southern specimens of plagiatus. The dorsal hook couldn’t be seen before the exuvia was cleaned.

No. 3 | Stylurus plagiatus | exuvia (dorsal)

The flat labium doesn’t cover the face, as shown in Photo No. 4 and 5.

No. 4 | Stylurus plagiatus | exuvia (ventral)

Photo No. 5 shows a close-up of the prementum. Each labial palp features at least three (3) teeth in addition to the end hook. The greatest width of the prementum is approximately four-fifths (4/5) of its length.

No. 5 | Stylurus plagiatus | exuvia (prementum)

This specimen is confirmed as an exuvia from a Russet-tipped Clubtail dragonfly (Stylurus plagiatus).

The Backstory

Photo No. 6, featured in a recent blog post entitled Getting Started, is focused on abdominal segment nine (S9).

This specimen may need to be cleaned in order to see more clearly some key field markers used for identification.

No. 6 | Potomac River, Fairfax County, VA | odonate exuvia

The specimen was soaked in soapy water for at least 24 hours. A plastic spoon was used to scoop the exuvia from the water bath and transfer it to a dry plastic tray. Then a soft artist’s paintbrush was used to clean the exuvia, with extra attention on abdominal segment nine (S9). Two damselfly exuviae are soaking in the same water bath, shown below. Other useful tools include a magnifying glass and a plastic toothpick.

The odonate exuviae cleaning station at BoG Photo Studio.

The exuvia is pliable after soaking in water for at least 24 hours. After the specimen was cleaned, it was posed and allowed to dry for another day. The handle of a plastic spoon is a good drying rack that makes it easier to pose the legs. The Stylurus plagiatus exuvia is shown in the following photograph. The broken leg resting on the handle of the spoon was attached to the body only by spider web.

Stylurus plagiatus exuvia, posed on the handle of a plastic spoon.

Tech Tips

The following equipment was used to shoot Photo No. 1, 2 and 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); and Canon MT-26EX-RT Macro Twin LitePhoto No. 3 and 5: Canon EOS 5D Mark II digital camera, in manual mode; Canon MP-E 65mm Macro lens (manual focus only, set for 2x magnification); and Canon MT-26EX-RT Macro Twin Lite. A Sunpak LED-160 Video Light (with a white translucent plastic filter) was used for some photos.

A Panasonic Lumix DMC-FZ150 superzoom bridge camera was used to take photos of the odonate exuviae cleaning station.

Adobe Photoshop CC 2017 was used to annotate selected images.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

Getting started

February 26, 2018

Michael Powell, a good friend and fellow Northern Virginian, collected several odonate exuviae during a photowalk along the Potomac River in Fairfax County, Virginia USA.

The four exuviae that Mike collected are stored in one of those empty containers of Philadelphia cream cheese spread that I endorsed in a recent blog post. I shot several quick-and-dirty photographs of the exuviae, without removing them from the small plastic tub. Usually I wouldn’t publish photos of this quality. The photos are like a sketch pad that will be used to make a tentative plan for photographing the specimens and attempting to identify them to the genus and species level, if possible.

Spoiler Alert: If you can identify any of the exuviae featured in this post, then PLEASE DON’T TELL ME! I enjoy the challenge of solving the mystery of their identity. Thank you!

Dragonfly exuviae

Mike collected two dragonfly exuviae that are from the Family Gomphidae (Clubtails), as indicated by a flat labium that doesn’t cover the face as well as club-like antennae.

My working theory is the first specimen might be an exuvia from an Eastern Ringtail dragonfly (Erpetogomphus designatus).

Potomac River, Fairfax County, VA | odonate exuvia

Post Update: The identity of the first specimen is confirmed as an Erpetogomphus designatus exuvia.

The next exuvia appears to be a member of the genus Stylurus, possibly plagiatus (Russet-tipped Clubtail).

Potomac River, Fairfax County, VA | odonate exuvia

The preceding photo was focused on the head; the following photo was focused on abdominal segment nine (S9). This specimen may need to be cleaned in order to see more clearly some key field markers used for identification.

Potomac River, Fairfax County, VA | odonate exuvia

Post Update: The identity of the first specimen is confirmed as a Stylurus plagiatus exuvia.

Damselfly exuviae

It is relatively easy to identify damselflies (Suborder Zygoptera) to the family level based upon the shape of the prementum. Both damselfly exuviae that Mike collected are members of the Family Coenagrionidae (Narrow-winged Damselflies).

It is more challenging to identify damselfly specimens to the genus/species level. In this case, possible genera include Argia (Dancers), Enallagma (American Bluets), and Ischnura (Forktails).

Potomac River, Fairfax County, VA | odonate exuvia

The last damselfly exuvia is smaller than the first. It will need to be soaked in soapy water for at least 24 hours in order to make the specimen pliable so it can be re-posed before it is photographed.

Potomac River, Fairfax County, VA | odonate exuvia

Copyright © 2018 Walter Sanford. All rights reserved.

Familiar Bluet damselfly (female)

February 2, 2018

A Familiar Bluet damselfly (Enallagma civile) was spotted near a drainage ditch at a remote location in Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

The damselfly appears to be eating a smaller black insect, possibly a spider.

Editor’s Note: Sincere thanks to Mike Boatwright for verifying my tentative identification of the damselfly.

Copyright © 2018 Walter Sanford. All rights reserved.

Dragonflies and Damselflies (poster, slideshow)

January 3, 2018

 

D R A G O N F L I E S  A N D  D A M S E L F L I E S
HUNTLEY MEADOWS PARK

W A L T E R  S A N F O R D
Educator | Naturalist | Photographer

 

Copyright © 2018 Walter Sanford. All rights reserved.


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