Posts Tagged ‘Virginia’

MYN – Eastern Amberwing exuvia (anal pyramid)

March 9, 2020

An Eastern Amberwing dragonfly (Perithemis tenera) exuvia was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.

65mm (3x magnification) | ISO 100 | f/8 | 1/200 s | 0 ev

Look closely at the full-size version of the preceding photo, showing a close-up of the anal pyramid at 3x magnification. Notice the cerci are approximately half as long as the epiproct and slightly less than half the length of the paraprocts. It’s a close call, but the latter field mark indicates Family Libellulidae (Skimmers).

A step-by-step identification guide (to the species level) will be published in a follow-up post. Stay tuned!

Related Resources

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – S. plagiatus exuvia (ventral composite)

March 4, 2020

Russet-tipped Clubtail dragonfly (Stylurus plagiatusexuvia was collected by Joe Johnston on 17 July 2019 along Aquia Creek in Stafford County, Virginia USA.

17 JUL 2019 | Aquia Creek | Stylurus plagiatus | exuvia (ventral view)

Related Resources

Tech Tips

This specimen was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. I used the new variation on my old MYN studio rig and I’m still satisfied with the results.

Four photos were used to create a composite image: one photo focused on the thorax; and three other photos focused on abdominal segments two-three (S2-S3), seven (S7), and nine (S9).

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Stylurus plagiatus exuvia (composite)

March 2, 2020

Russet-tipped Clubtail dragonfly (Stylurus plagiatusexuvia was collected by Joe Johnston on 17 July 2019 along Aquia Creek in Stafford County, Virginia USA.

Two key field marks can be used to quickly identify both the genus and species of this specimen. Notice that abdominal segment nine (S9) is elongated, strongly suggesting this individual is a member of the genus Stylurus. The large dorsal hook of abdominal segment nine (S9) that overhangs segment 10 (S10) is a key marker for southern specimens of plagiatus.

Related Resources

Tech Tips

This specimen was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. I used the new variation on my old MYN studio rig and I’m still satisfied with the results.

Four photos were used to create a composite image: one photo focused on the head; and three other photos focused on abdominal segments five (S5), seven-eight (S7-S8), and 10 (S10).

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Stylurus plagiatus exuvia

February 28, 2020

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) exuvia was collected by Joe Johnston on 17 July 2019 along Aquia Creek in Stafford County, Virginia USA.

17 JUL 2019 | Aquia Creek | Stylurus plagiatus | exuvia (face-head)

Notice the specimen has a flat labium that doesn’t cover the face (not mask-like), as shown in the preceding photo. This field mark indicates the exuvia is from either Family Aeshnidae (Darners) or Family Gomphidae (Clubtails). Other field marks, including club-like antennae and the shape of the body, indicate this individual is a species of clubtail.

My next blog post will feature a dorsal-lateral view of the exuvia that clearly shows the field marks that indicate both genus and species.

Related Resources

Tech Tips

This specimen was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. I used the new variation on my old MYN studio rig and I’m still satisfied with the results.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Unknown dragonfly exuvia (redux)

February 26, 2020

This blog post features more photos of an exuvia from an unknown species of odonate that was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

07 AUG 2019 | Aquia Creek | dragonfly exuvia (dorsal view)

The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.

07 AUG 2019 | Aquia Creek | dragonfly exuvia (ventral view)

I’m having a hard time seeing the cerci clearly. If I’m seeing what I think I’m seeing, then the cerci are at least half as long as the paraprocts and the exuvia is from Family Corduliidae (Emeralds).

In order to verify my tentative identification, I need to use a higher magnification macro lens (such as my Canon MP-E 65mm Macro lens) in order to shoot a close-up view of the anal pyramid/terminal appendages (see inset diagram, lower-left corner).

Related Resource: MYN – Dragonfly exuvia (unknown species)

Tech Tips

This specimen was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique. I used the new variation on my old MYN studio rig and I’m still satisfied with the results.

Copyright © 2020 Walter Sanford. All rights reserved.

MYN – Dragonfly exuvia (unknown species)

February 24, 2020

An exuvia from an unknown species of odonate was collected by Joe Johnston on 07 August 2019 along Aquia Creek at Channel Marker No. 34, Stafford County, Virginia USA.

The specimen is definitely a dragonfly, probably from either Family Corduliidae (Emeralds) or Family Libellulidae (Skimmers).

07 AUG 2019 | Aquia Creek | dragonfly exuvia (face-head-dorsal view)

This relatively small exuvia is ~1.2 to 1.3 cm in length. Notice the dorsal hooks on the exuvia are “cultriform,” that is, shaped like a pruning knife.

07 AUG 2019 | Aquia Creek | dragonfly exuvia (lateral view)

Related Resource: Odonate exuviae collecting sites [along Aquia Creek]

Tech Tips

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

I experimented with a new variation on my old MYN studio rig. The new set-up seems to work well, although the question remains “Does it work well consistently?” I added a second external flash unit that is used to backlight a piece of translucent white plastic (the background), and I physically separated the clear plastic “stage” from the white background. More info and photos will be featured in a follow-up blog post.

Copyright © 2020 Walter Sanford. All rights reserved.

Data mining for Autumn Meadowhawk

October 28, 2019

This is a follow-on to my last blog post, Are adult Autumn Meadowhawks arboreal?

Data mining can be used to recognize patterns in official records of field observations by many amateur and professional odonate hunters, confirmed by experienced vetters.

Let’s begin by looking at the adult flight period for Autumn Meadowhawk (Sympetrum vicinum), the target species for a proposed field study during 2020 at the Vermont Institute of Natural Science.

Adult Flight Period

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for Autumn Meadowhawk (S. vicinum) is from May 28 to January 03. The species is classified as “common.” Its habitat is “ponds.”

Bear in mind, Dr. Roble’s records are for the entire state, therefore the adult flight period for S. vicinum seems to be longer than it is in reality. The adult flight period for a single site is probably shorter. For example, according to records for Northern Virginia maintained by Kevin Munroe, former manager of Huntley Meadows Park, the adult flight period for Autumn Meadowhawk is June 13 to December 10 (seen most September to October).

DSA Odonata Central Records

What is shown by a deep-dive into the Dragonfly Society of the Americas Odonata Central records database for Autumn Meadowhawk in the Commonwealth of Virginia?

There are currently 38 confirmed records for S. vicinum in Virginia, as shown by the following distribution map.

Source Credit: Abbott, J.C. 2006-2019. OdonataCentral: An online resource for the distribution and identification of Odonata. Available at http://www.odonatacentral.org. (Accessed: October 27, 2019).

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

Analysis

There are 14 records for teneral/immature adult Autumn Meadowhawk, ranging from 30 May to 19 August: May (1); June (5); July (5); August (3). Notice that the greatest cluster of records for teneral/immature adults occurs in June and July. There are a few records for mature adults toward the end of this time period and no records for mating pairs.

There are 24 records for mature adult Autumn Meadowhawk, ranging from 07 August to 03 January: August (2); September (5); October (13); November (1); December (2); January (1). Only a few records for teneral/immature adults occur at the beginning of this time period. The greatest cluster of records for mature adults occurs in October. Seven (7) of the records throughout the time period are for mating pairs, beginning in September; the greatest cluster of records for mating pairs also occurs in October.

What are the take-aways?

38 records is an admittedly small sample size. In the opinion of the author, patterns in the data are muddied by analyzing data for the entire state rather than a single location. There is almost certainly a south-to-north pattern in dates of emergence, mating, and disappearance for any given species, as well as atypical patterns resulting from micro-climates that exist throughout the state.

All of that being said, the data in the DSA Odonata Central records database for Virginia is consistent with my first-hand observations in Northern Virginia showing that Autumn Meadowhawk emerges in mid- to late-June, disappears for two- to three months, and returns to the ground/water when it’s time to mate during fall.

One big question remains to be answered: Where do adult Autumn Meadowhawks go when they disappear soon after emergence — do they live in the forest canopy? One thing we know is certain: There are few if any official records for mature adult Autumn Meadowhawk on the ground during mid- to late-summer. Food for thought.

Related Resource: Are adult Autumn Meadowhawks arboreal?

Copyright © 2019 Walter Sanford. All rights reserved.

Flashback to late-May 2019

September 16, 2019

Look closely at the following photo — there’s a dragonfly in there somewhere!

21 May 2019 | PNC. William County, VA | Lancet Clubtail (female)

A Lancet Clubtail dragonfly (Phanogomphus exilis) was spotted by Gary Myers at an undisclosed location in Prince William County, Virginia USA. The dragonfly is perched on leaf litter in a seepage area upstream from a small pond.

Female and male terminal appendages

This individual is a female, as indicated by her rounded hind wings and terminal appendages. (Notice the “bonus bug” to the right of the label for cercus.)

21 May 2019 | PNC. William County, VA | Lancet Clubtail (female)

Contrast the appearance of those female field marks with males of the same species.

03 MAY 2017 | Fairfax County, VA | Lancet Clubtail (male)

Related Resource: Odonate Terminal Appendages — single-topic field guides for dragonflies and damselflies featuring both text and annotated photos.

Copyright © 2019 Walter Sanford. All rights reserved.

“Grays” love them some me!

August 14, 2019

2019 was a record-setting year for observing Gray Petaltail dragonflies (Tachopteryx thoreyi) with Mike Powell at an undisclosed location in Prince William County, Virginia USA.

  • 21 May 2019 was the day that we observed at least a dozen (12+) Gray Petaltail — the most on any day during 2019.
  • 14 June 2019 was the day that the most “Grays” landed on me, including one female and two males plus some others that didn’t perch long enough to be photographed by either Mike or me.

Female

The first individual is a female, as indicated by her rounded hind wings and terminal appendages. She is perched on the front of my gray-green shirt.

Photo used with permission from Mike Powell.

Please get this man to a barber STAT! On the other hand, there isn’t much else that can be done about the face. As you can see, I’m the owner of a high mileage “vehicle” — fortunately it still runs good!

Photo used with permission from Mike Powell.

Males

The next individual is a male, as indicated by his “indented” hind wings, and terminal appendages. He is perched on the right sleeve of my shirt.

Photo used with permission from Mike Powell.

The same male is shown in the following image. This photo is my favorite in the gallery.

Photo used with permission from Mike Powell.

The last individual, possibly/probably a male, is perched on my off-white bucket hat. The “Gray” was doing a Vulcan mind-meld with me by using specialized contact via the tips of his legs.

Photo used with permission from Mike Powell.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

More “Grays” on me

August 12, 2019

Well, really just one “Gray.” Gray Petaltail dragonfly (Tachopteryx thoreyi), that is. Perched on my … er, hip. This individual is a female, as indicated by her rounded hind wings and terminal appendages.

Guest photographer Michael Powell shot both images during a photowalk with me on 21 May 2019 at an undisclosed location in Prince William County, Virginia USA.

The following photo set provides a brief example of what we call “working the shot.” The first photo is what some other ode hunters call the “record shot,” meaning get a shot, any shot of the subject in case it flies away and is never seen again.

Photo used with permission from Mike Powell.

Slowly Mike moved closer to get the shot he wanted, shown below.

Photo used with permission from Mike Powell.

The Backstory

21 May 2019 was a great day for spotting Gray Petaltail dragonflies during a long, productive photowalk with Michael Powell at two locations: along a small stream in the forest; and around a small seep-fed pond. At least a dozen (12+) T. thoreyi were observed during the day, including two “Grays” that landed on Mike.

As we were walking toward Mike’s car at the end of the day, I was feeling disappointed that we hadn’t taken any photos of T. thoreyi perched on me. That’s when I noticed a Gray Petaltail perched on a fence rail. Before I was able to take a picture of the dragonfly, she flew from the fence rail to a new perch on my backside. Fortunately Mike was close behind me and was able to shoot the good photos featured in this blog post. Needless to say, I suffered as the butt of many jokes related to my indelicate circumstance!

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.


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