Posts Tagged ‘Occoquan Regional Park’

MYN – Anisoptera exuvia (species unknown)

March 11, 2020

An Anisoptera exuvia (species unknown) was collected near a small pond at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

This individual probably is a member of the Family Libellulidae (Skimmers), as indicated by its anal pyramid. The small pond where the specimen was collected is perfect habitat for skimmers.

01 JUN 2019 | ORP | Anisoptera exuvia (dorsallateral view)

Related Resource: Another unknown species of odonate exuvia – a blog post by Walter Sanford featuring a “one-off” photo (that is, not a composite image) of the same specimen.

Tech Tips

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

Two photos were used to create a composite image: one photo focused on the head; and another photo focused on abdominal segments seven (S7) through nine (S9).

My Canon EOS 5D Mark II is a full-frame DSLR digital camera. RAW images are 5616 × 3744 pixels. The dimensions of the composite image are 5589 × 3743 pixels, that is, essentially full-frame. It’s usually necessary to crop composite images, at least a little, because the individual photos used to create the composite don’t align perfectly, even when the camera is mounted on a tripod (as it was in this case).

For what it’s worth, the following camera settings were used to shoot both photos: 100mm; ISO 100; f/8; 1/200 s; 0 ev. I need to tweak the settings a little in order to find the “sweet spot” for this camera/lens combo: the white background was slightly over-exposed; and the subject was slightly under-exposed. Of course that means I need to tweak the flash power for the backlights and add one or more additional external flash units for more fill flash. Overall, I’m fairly satisfied with the results of my first attempt using the MYN technique with this camera rig.

Copyright © 2020 Walter Sanford. All rights reserved.

What is it?

February 7, 2020

It’s time for another exciting edition of “What is it?” Well, what is shown in the following photograph? If you think you know what it is, then please leave a comment. The answer will be provided in a post update.

03 FEB 2020 | Occoquan Regional Park | What is it?

Post Update

Congratulations to the two readers who correctly identified the mantis ootheca shown in the preceding photo! (See Comments/Responses, below.)

This is a Chinese Mantis (Tenodera sinensis) egg case, as indicated by the distinctive roundish shape of the ootheca. Chinese Mantis is a non-native species.

Copyright © 2020 Walter Sanford. All rights reserved.

Skunk cabbage flowers

February 5, 2020

The following photo gallery shows skunk cabbage (Symplocarpus foetidus) flowers in a forest seep located at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

This is ideal habitat for Gray Petaltail dragonfly (Tachopteryx thoreyi) larvae, and in fact, numerous adult “Grays” have been observed along a sunny trail near this location. Seeps are home for some species of larvae from Family Cordulegastridae (Spiketails) as well.

03 FEB 2020 | ORP | forest seep, with skunk cabbage flowers

03 FEB 2020 | ORP | forest seep, with skunk cabbage flowers

03 FEB 2020 | ORP | forest seep, with skunk cabbage flowers

03 FEB 2020 | ORP | forest seep, with skunk cabbage flowers

The last photo shows the same location during early Summer 2019. The plant with broad green leaves is skunk cabbage.

01 JUN 2019 | ORP | forest seep, with skunk cabbage

The following quote is perhaps the best description of a forest seep that I’ve read.

[Some] small tributaries … have their sources in numerous woodland seeps. While a few of these perennial springs bubble up out of the ground, most arise in moist hillside patches with lots of decaying leaf litter and luxuriant stands of skunk cabbage. Source Credit: White, Harold B., III. Natural History of Delmarva Dragonflies and Damselflies (Cultural Studies of Delaware and the Eastern Shore) (Kindle Locations 1213-1215). University Press Copublishing Division. Kindle Edition.

Related Resource: Skunk Cabbage: First Flower of the Year… by Alonso Abugattas, Capital Naturalist blog. The blog post includes an embedded link to an informative video by Mr. Abugattas: Capital Naturalist: Skunk Cabbage Blooming (3:58).

Copyright © 2020 Walter Sanford. All rights reserved.

Another unknown species of odonate exuvia

November 4, 2019

Another odonate exuvia was collected by Michael Powell during a photowalk with me on 01 June 2019 at Occoquan Regional Park, Fairfax County, Virginia USA. The genus and species is unknown.

Occoquan Regional Park | unknown species | exuvia (face-head)

This specimen might be a member of Family Libellulidae (Skimmers), as indicated by its labium (face mask) and pointy eyes.

Although this exuvia looks similar to the other one that Mike collected on 01 June 2019, it’s smaller and probably not another Slaty Skimmer (L. incesta) exuvia. Many species of skimmers are habitat generalists; the small pond where both exuviae were found is a perfect spot for many members of this family.

The photo (shown above) is a one-off, not a composite image. I plan to create higher quality composite images of this exuvia, shown from all viewpoints including dorsal, ventral, and lateral views. The composite images and one or more dichotomous keys will be used to attempt to identify the genus/species of the specimen.

Related Resource: Vimeo video: Identifying dragonfly larva to family (8:06).

Tech Tips

The following equipment was used to shoot the quick-and-dirty macro photograph featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/16; 1/180s.

Godox X2TF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control two off-camera external flash units set for radio slave mode: Godox TT685F Thinklite TTL Flash (manual mode); and Godox TT685o/p Thinklite Flash for Olympus/Panasonic Cameras (manual mode). Both flash units were fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image.

Copyright © 2019 Walter Sanford. All rights reserved.

Unknown species of odonate exuvia (ventral)

October 21, 2019

This post features another photo of an odonate exuvia collected by Michael Powell during a photowalk with me on 01 June 2019 at Occoquan Regional Park, Fairfax County, Virginia USA. The photo is a one-off (not a composite image) showing the ventral view of the exuvia.

The genus and species is unknown. This specimen might be a member of Family Libellulidae (Skimmers), probably Slaty Skimmer (Libellula incesta).

Occoquan Regional Park | unknown species | exuvia (ventral)

Related Resource: Vimeo video: Identifying dragonfly larva to family (8:06).

Tech Tips

The following equipment was used to shoot the quick-and-dirty macro photograph featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-16 extension tube; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/16; 1/180s.

Godox X2TF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control two off-camera external flash units set for radio slave mode: Godox TT685F Thinklite TTL Flash (manual mode); and Godox TT685o/p Thinklite Flash for Olympus/Panasonic Cameras (manual mode). Both flash units were fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image.

Copyright © 2019 Walter Sanford. All rights reserved.

Unknown species of odonate exuvia, revisited

October 18, 2019

This post features more photos of an odonate exuvia collected by Michael Powell during a photowalk with me on 01 June 2019 at Occoquan Regional Park, Fairfax County, Virginia USA. Both photos are one-offs, not composite images.

The genus and species is unknown. This specimen might be a member of Family Libellulidae (Skimmers).

Occoquan Regional Park | unknown species | exuvia (lateral)

Mid-dorsal hooks are present on some abdominal segments. Lateral spines are located on abdominal segments eight and nine (S8-9).

Occoquan Regional Park | unknown species | exuvia (dorsal)

I still need to take close-up photos of the anal pyramid and shoot photos of the ventral view before I attempt to identify the genus/species of the specimen using one or more dichotomous keys.

Related Resource: Vimeo video: Identifying dragonfly larva to family (8:06).

Tech Tips

The following equipment was used to shoot the quick-and-dirty macro photograph featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-16 extension tube; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/16; 1/180s.

Godox X2TF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control two off-camera external flash units set for radio slave mode: Godox TT685F Thinklite TTL Flash (manual mode); and Godox TT685o/p Thinklite Flash for Olympus/Panasonic Cameras (manual mode). Both flash units were fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image.

Copyright © 2019 Walter Sanford. All rights reserved.

Unknown species of odonate exuvia

October 16, 2019

An odonate exuvia was collected by Michael Powell during a photowalk with me on 01 June 2019 at Occoquan Regional Park, Fairfax County, Virginia USA. The genus and species is unknown.

Occoquan Regional Park | unknown species | exuvia (face-head)

This specimen might be a member of Family Libellulidae (Skimmers), as indicated by its labium (face mask) and pointy eyes.

The photo (shown above) is a one-off, not a composite image. I plan to create higher quality composite images of this exuvia, shown from all viewpoints including dorsal, ventral, and lateral views. The composite images and one or more dichotomous keys will be used to attempt to identify the genus/species of the specimen.

Related Resource: Vimeo video: Identifying dragonfly larva to family (8:06).

Tech Tips

The following equipment was used to shoot the quick-and-dirty macro photograph featured in this post: Fujifilm X-T1 digital camera; Fujifilm MCEX-11 extension tube; and Fujinon XF80mm macro lens plus lens hood. The camera was set for both manual exposure and manual focus. That’s right, a switch on the camera body is used to set the type of focus. It’s a Fujifilm thing. Camera settings: focal length 80mm (120mm, 35mm equivalent); ISO 200; f/16; 1/180s.

Godox X2TF radio flash trigger, mounted on the hotshoe of my X-T1, was used to control two off-camera external flash units set for radio slave mode: Godox TT685F Thinklite TTL Flash (manual mode); and Godox TT685o/p Thinklite Flash for Olympus/Panasonic Cameras (manual mode). Both flash units were fitted with a Lastolite Ezybox Speed-Lite 2 flash modifier.

Adobe Photoshop CC 2017 was used to spot-heal and sharpen the image.

Copyright © 2019 Walter Sanford. All rights reserved.

“Grays” on me

July 15, 2019

“Grays” on me? No, don’t eat me! (See what I did there?)

This post features images from guest photographer Michael Powell, taken during a photowalk with me at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

The photos show two different male Gray Petaltail dragonflies (Tachopteryx thoreyi) perched on me.

Photo used with permission from Mike Powell.

The last photo shows a male Gray Petaltail perched on my bucket hat. Look closely at the full-size version of the photo. Notice the dragonfly appears to be grazing upon a smaller insect. (See? I did it again!)

Photo used with permission from Mike Powell.

I call the preceding photo “Wilson Wilson” because it reminds me of a discussion between Tim “The Tool Man” Taylor and his next-door neighbor Wilson Wilson about a flying saucer that Wilson saw. See Home Improvement: Believe It or Not Clip (1:31).

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Widow Skimmer (immature male)

July 12, 2019

A Widow Skimmer dragonfly (Libellula luctuosa) was spotted near a small pond at Occoquan Regional Park (ORP), Fairfax County, Virginia USA.

01 JUN 2019 | ORP | Widow Skimmer (immature male)

This individual is an immature male, as indicated by his coloration and terminal appendages. He is hunkered down in a hidey-hole, almost out of sight.

Copyright © 2019 Walter Sanford. All rights reserved.

Gray Petaltail dragonfly (male)

July 3, 2019

The following Gray Petaltail dragonfly (Tachopteryx thoreyi) — spotted in a sunny clearing along a small stream in the forest at an undisclosed location in Prince William County, Virginia USA — is a male, as indicated by his “indented” hind wings, and terminal appendages.

14 JUN 2019 | PNC. William County, VA | Gray Petaltail (male)

Actionable Intel

I looked for Gray Petaltail for years without finding one. (Looking for love in all the wrong places?) For habitat-specific odonates such as T. thoreyi, it’s all about location, location, location. I was familiar with the standard guidance in all the field guidebooks regarding ideal habitat for Gray Petaltail, but it wasn’t until I actually saw the right habitat in the wild — and recognized it for what it is — that I began to find Grays in relatively large numbers. Book learning is good (as Jethro would say), but there’s no substitute for real-world experience.

For example, the following photograph shows a forest seep located at Occoquan Regional Park (ORP), Fairfax County, Virginia USA. The plant with broad green leaves is skunk cabbage (Symplocarpus foetidus). This is ideal habitat for T. thoreyi, and in fact, one or more “Grays” were observed along a sunny trail near this location, including a male that landed on my friend Mike Powell.

01 JUN 2019 | ORP | forest seep, with skunk cabbage

The following quote is perhaps the best description of a forest seep that I’ve read.

[Some] small tributaries … have their sources in numerous woodland seeps. While a few of these perennial springs bubble up out of the ground, most arise in moist hillside patches with lots of decaying leaf litter and luxuriant stands of skunk cabbage. Source Credit: White, Harold B., III. Natural History of Delmarva Dragonflies and Damselflies (Cultural Studies of Delaware and the Eastern Shore) (Kindle Locations 1213-1215). University Press Copublishing Division. Kindle Edition.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.


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