Posts Tagged ‘Prince William County’

Dark and moody

November 19, 2021

I spotted an emergent Uhler’s Sundragon (Helocordulia uhleri) during a photowalk along a mid-size stream at an undisclosed location in Prince William County, Virginia USA. The following photograph shows the exuvia from which the teneral adult eclosed.

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

In the opinion of the author, larvae (nymphs)/exuviae from Family Corduliidae (Emeralds) and Family Libellulidae (Skimmers) can be challenging to differentiate and identify to the family level.

One way to differentiate Emerald from Skimmer larvae/exuvia is to look for a “ventromedial groove” in the prementum: it’s probably Corduliidae (Emeralds) if there is a ventromedial groove; it’s probably Libellulidae if there isn’t.

Look closely at a version of the preceding photo that was reformatted, rotated, and cropped to show an enlarged view of the prementum. You should notice a ventromedial groove on the basal half of the prementum, indicating this specimen is a member of Family Corduliidae (Emeralds).

13 APR 2021 | PNC. Wm. County, VA | Uhler’s Sundragon | exuvia (ventral)

Three raised structures on the underside of the prementum remind me of the hood ornament on a 1949 Lincoln automobile. (No, I wasn’t alive in 1949!)

Related Resources

Tech Tips

One reason I underexposed the photo is to add definition to the ventromedial groove and avoid overexposing the black background.

I prefer a white background for photographing odonate exuviae. Using a black background proved to be more challenging than I expected. More later in a follow-up blog post.

Copyright © 2021 Walter Sanford. All rights reserved.

Bridge across Quantico Creek

August 3, 2021

The following photos show a small wooden bridge across Quantico Creek, near Burma Road in Prince William Forest Park, Prince William County, Virginia USA.

13 MAY 2021 | PNC. Wm. Forest Park | bridge across Quantico Creek

If you like bridges that bounce when you walk across them, then this is the bridge for you! I prefer bridges that are rock-solid.

13 MAY 2021 | PNC. Wm. Forest Park | bridge across Quantico Creek

Related Resource: All posts in my blog tagged with the word “bridge.”

Copyright © 2021 Walter Sanford. All rights reserved.

Zebra Swallowtail butterfly

July 16, 2021

Zebra Swallowtail butterfly (Eurytides marcellusProtographium marcellus) was spotted near a small pond at an undisclosed location in Prince William County, Virginia USA.

17 JUN 2021 | Prince William County | Zebra Swallowtail

Notice the Zebra Swallowtail lost part of one of its tails, possibly the result of a close encounter with predator.

Copyright © 2021 Walter Sanford. All rights reserved.

I was common, when common wasn’t cool.

June 8, 2021

Common Whitetail dragonfly (Plathemis lydia) was observed during a photowalk along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This individual is an immature male, as indicated by his mostly brown coloration, pattern of wing spots, and terminal appendages.

13 MAY 2021 | PNC. Wm. County | Common Whitetail (immature male)

This photo is one of a few “warm-up shots” I took at the outset of my photowalk. I think it’s a good idea to be sure your camera gear is working as expected before you blow an opportunity to photograph something rare to uncommon by fiddling with camera settings.

Copyright © 2021 Walter Sanford. All rights reserved.

Ashy Clubtail dragonfly (male)

May 28, 2021

An Ashy Clubtail dragonfly (Phanogomphus lividus) was spotted during a photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

13 MAY 2021 | Prince William County, VA | Ashy Clubtail (male)

This individual is a male, as indicated by his terminal appendages. A dorsal view of the same species shows the hind wings of Ashy males are “indented.” The male was perched on rocks, sand, and leaf litter deposited along the edges of the stream channel.

13 MAY 2021 | Prince William County, VA | Ashy Clubtail (male)

I’ve seen Ashy Clubtail dragonflies many times, but this was the first time I noticed their unusual flight pattern. Imagine a one-car roller coaster, going up and down smoothly while moving forward slowly. That’s the best way I can describe what I saw. You’ll recognize it when you see it — very distinctive!

My buddy Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, told me Lancet Clubtail (Phanogomphus exilis) has the same flight pattern.

Tech Tips

Both photos are full-frame (4,000 x 3,000 pixels), that is, uncropped. I considered cropping the photos to make the dragonfly appear larger. I decided to post the uncropped photos to show the smallish size of Ashy Clubtail more authentically. Click on each photo in order to see a full-size version that you can zoom-in on to see more detail.

Copyright © 2021 Walter Sanford. All rights reserved.

Turn! Turn! Turn!

May 21, 2021

Perceptive observers of nature notice gradual changes that indicate the change of season.

To everything (turn, turn, turn)
There is a season (turn, turn, turn)
And a time to every purpose, under heaven.
Source Credit: Turn! Turn! Turn! Song by The Byrds

For example, sighting a Spangled Skimmer dragonfly (Libellula cyanea) is a sure sign the subtle transition from spring to summer is underway.

13 MAY 2021 | PNC. Wm. County, VA | Spangled Skimmer (teneral female)

One of my mantras for wildlife photography is “Get a shot, any shot; refine the shot.” The preceding photo is one I took when I noticed the dragonfly; the following photo is one I took after slowly working my way into position for a better shot. Notice the dragonfly changed positions too, moving from one perch to another when I moved closer to her.

13 MAY 2021 | PNC. Wm. County, VA | Spangled Skimmer (teneral female)

This individual is a female, as indicated by her coloration and terminal appendages.

Copyright © 2021 Walter Sanford. All rights reserved.

Stream Cruiser dragonfly (female)

May 18, 2021

A Stream Cruiser dragonfly (Didymops transversa) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

This individual is a female, as indicated by her thick abdomen and terminal appendages.

13 MAY 2021 | Prince William County, VA | Stream Cruiser (female)

The female was perched in a large field near the same location where Mike Powell found a Stream Cruiser exuvia on 13 April 2021.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Waiting for the sky to clear

May 11, 2021

A picturesque dam was visited during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

13 APR 2021 | Prince William County, VA

As you can see, the sky was completely overcast when the photograph was taken and the weather was cool and breezy. Not ideal conditions for odonate hunting, but hey, sometimes you just have to make lemonade from lemons by stopping to enjoy the beautiful scenery!

Tech Tips

I used Adobe Photoshop Lightroom CC to edit the preceding photo. A graduated filter was used to enhance detail in clouds in the sky without making the shadows too dark in the rest of the image. The area affected by the graduated filter is highlighted in red, as shown in the following screen capture: I decreased the Exposure, affecting the clouds/sky); and increased the Shadows, affecting the tree tops.

The last screen capture shows the global adjustments I made to the entire photo using the Develop module — notice these settings are different from the settings for the selective adjustments I made using the graduated filter, shown above.

Related Resources

Two complementary videos demonstrate how to use the graduated filter in Adobe Lightroom: Matt Kloskowski shows a practical example of how to use a graduated filter to enhance the sky; Julieanne Kost provides an excellent tutorial that explains in detail how the graduated filter works.

Copyright © 2021 Walter Sanford. All rights reserved.

Another female Uhler’s Sundragon

May 7, 2021

Before we move on from the early spring species of odonates, here are a couple of photos of another one of several female Uhler’s Sundragon dragonflies (Helocordulia uhleri) that were spotted during a photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

At first she wanted to play peek-a-boo.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (female)

After a while, both of us moved to a slightly different position that worked better for me to photograph the subject.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (female)

That reminds me of another one of my mantras for wildlife photography: Get a shot, any shot; refine the shot. In this case, that’s exactly what I did.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.

Uhler’s Sundragon dragonfly (emergent female)

April 27, 2021

Uhler’s Sundragon (Helocordulia uhleri) was spotted during a recent photowalk with Michael Powell along a mid-size stream at an undisclosed location in Prince William County, Virginia USA.

The dragonfly was perched on the exuvia from which it emerged; its cast skin was still clinging to a grass stem approximately six inches (6″) above the ground. The patch of grass was located two-to-three feet from the shoreline, where the stream current was slow-to-moderate. The stream bed was sandy and gently sloped near the site on land where the dragonfly larva stopped to eclose.

This individual is an emergent female, as indicated by her teneral appearance, rounded hind wings, terminal appendages, and subgenital plate.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (emergent female)

The subgenital plate is located on the ventral side of the abdomen beneath segment eight.

Underneath Segment 8 there is either an ovipositor or a subgenital plate, depending upon the species [of dragonfly]. Both structures are for laying eggs and extend over Segment 9 and possibly beyond. Source Credit: Dragonflies of the North Woods, by Kurt Mead.

Remember that “Segment 8 and 9” refers to abdominal segments eight and nine (of 10), numbered from front to back.

13 APR 2021 | Prince William County, VA | Uhler’s Sundragon (emergent female)

The following graphic from Dragonflies and Damselflies of the East by Dennis Paulson shows the shape of the subgenital plate on our emergent female matches Uhler’s perfectly.

Graphic used with written permission from Dennis Paulson.

True Detective

Generally speaking, teneral odonates are more challenging to identify than most mature adult dragonflies and damselflies. Full disclosure: Neither Mike nor I were certain of the identity of the emergent female when we were shooting photographs in the field. “Shoot first and ask questions later” is one of my mantras for wildlife photography.

The most reliable way to identify odonate larvae to the species level is to rear them to maturity and emergence, that is, unless you’re fortunate to find a larva emerging in the field. Since an exuvia is essentially a nearly perfect shell of the last instar, it can be used to identify other specimens of the same species by pattern matching.

In this case, I used the exuvia to reverse-engineer the identity of the teneral dragonfly. Look closely at a lateral view of the exuvia, as shown in the following photo taken by Mike Powell. Notice there are dorsal hooks on abdominal segments seven, eight, and nine (S7-9). This distinctive field mark confirms the identity of the species as H. uhleri.

Photo used with written permission from Michael Powell.

Also notice Mike’s photo shows a clear view of the emergent female’s terminal appendages, as well as the subgenital plate on the underside of her abdomen.

How it all began, and ended.

The sky was almost completely overcast and it was cool and windy when I spotted the emergent female. Mike Powell and I observed the dragonfly for quite a while and there was little noticeable progress. According to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, the process of emergence can take longer when the air temperature is cooler.

When the sky began clearing, Mike Powell and I decided to go to a nearby place where he had seen adult Uhler’s recently. Later the same day, we returned to the site of the emergent female; she was gone, so I collected the exuvia. I plan to publish a photo set of the exuvia in an upcoming blog post. To be continued.

Related Resources

Copyright © 2021 Walter Sanford. All rights reserved.


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