Archive for the ‘natural science’ Category

Virginia Bluebells

May 21, 2018

The following photographs show Virginia Bluebells (Mertensia virginica) growing in a valley meadow at Hemlock Overlook Regional Park in Fairfax County, Virginia USA.

23 APR 2018 | Hemlock Overlook Regional Park | Virginia Bluebells

The flowers seemed to be a little past peak, as shown in the following close-up view. Nonetheless, the sea of blue was spectacularly beautiful.

23 APR 2018 | Hemlock Overlook Regional Park | Virginia Bluebells

Related Resources

Tech Tips

I used my Panasonic Lumix DMC-FZ150 superzoom camera to shoot the landscape photo featured in this blog post. The camera was set for manual focus at the hyperfocal distance for an aperture of f/4, based upon the instructions provided in the excellent video tutorial by Graham Houghton, “Panasonic Lumix FZ camera easier manual focus method — super point-and-shoot tip.”

The color saturation was increased slightly for both photos during post-processing.

Copyright © 2018 Walter Sanford. All rights reserved.

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Springtime Darner (male claspers)

May 19, 2018

A Springtime Darner dragonfly (Basiaeschna janata) was spotted along Popes Head Creek at Hemlock Overlook Regional Park (HORP) in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and “indented” hind wings.

23 APR 2017 | HORP | Springtime Darner (male)

(See a full-size version of the original photo, without annotation.)

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”).

23 APR 2017 | HORP | Springtime Darner (male)

(See a full-size version of the original photo, without annotation.)

Editor’s Notes

The preceding photos are new, that is, previously unpublished. Both photos are full-frame (uncropped). Springtime Darners can be quite skittish. In this case, I was very close to an unusually cooperative model.

The last photo was shot using Aperture Priority. I prefer shooting in Shutter Priority, but I like to shoot a few shots using Aperture Priority whenever I can use either a monopod or tripod. In this situation, I improvised.

In addition to my photography gear, I usually carry a Coleman camp stool when I go photowalking. The small, lightweight folding chair is good for resting while waiting for “the game to come to me.” The camp stool also enables me to get closer to subjects either on- or near the ground, such as the Springtime Darner featured in this blog post. I think it’s easier to hold my camera rock-steady when I’m sitting on the chair with my elbows resting on my knees.

Copyright © 2018 Walter Sanford. All rights reserved.

Twin-spotted Spiketail (male claspers)

May 17, 2018

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”).

Male members of the Family Cordulegastridae (Spiketails), including male Twin-spotted Spiketail dragonflies (Cordulegaster maculata), have relatively small cerci (terminal appendages) that can be mistaken for female cerci.

Male dragonfly secondary genitalia, called hamules, are located below abdominal segments two and three (S2 and S3), as shown in the following annotated image. Hamules come in a variety of sizes and shapes, but their function is identical for all species of odonates.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

Brown Spiketail dragonfly (male claspers)

May 15, 2018

Brown Spiketail dragonflies (Cordulegaster bilineata) were spotted on two days during May 2018 at Occoquan Regional Park. Both individuals featured in this post are male, as indicated by their terminal appendages and slightly “indented” hind wings.

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”).

Notice the epiproct for Brown Spiketail is a wide “plate” that spans both cerci, as shown in the full-size version of the following annotated image.

Male dragonfly secondary genitalia, called hamules, are located below abdominal segments two and three (S2 and S3), as shown in the preceding annotated image. Hamules come in a variety of sizes and shapes, but their function is identical for all species of odonates. Some species of dragonflies and damselflies — such as Ashy Clubtail versus Lancet Clubtail and Southern Spreadwing versus Sweetflag Spreadwing, to name a few — can be differentiated/identified with certainty only by examining the hamules under magnification.

Copyright © 2018 Walter Sanford. All rights reserved.

More male Brown Spiketails

May 13, 2018

Two more Brown Spiketail dragonflies (Cordulegaster bilineata) were spotted on 11 May 2018 at Occoquan Regional Park. Both individuals are male, as indicated by their terminal appendages and “indented” hind wings.

Male 1

The first photo of Male 1 is the “record shot.”

The next photo shows a dorsal view of the same individual.

Male 2

The first photo of Male 2 is the “record shot.”

The next photo is my favorite in this post. Notice the eye color of this individual is more green than brown. The difference in eye color could be caused by natural variation or it might indicate that Male 2 is more mature than Male 1.

Although Brown Spiketails seem to prefer perching in sunny places, the last photo shows the male hanging in shade rather than direct sunlight.

Copyright © 2018 Walter Sanford. All rights reserved.

Brown Spiketail dragonfly (male)

May 11, 2018

My first Brown Spiketail dragonfly (Cordulegaster bilineata) was a female that I photographed on 01 May 2013 at Meadowood Recreation Area in Fairfax County, Virginia USA. That was the last Brown Spiketail I saw for the next five years. As it turns out, spiketails are relatively uncommon in Northern Virginia. Who knew?

Soon after Mike Powell and I photographed one or two Twin-spotted Spiketail dragonflies (Cordulegaster maculata) on 07 May 2018 at Occoquan Regional Park, we spotted a male Brown Spiketail perched in a sunny place along the same dirt/gravel trail where we had seen the Twin-spotted.

As a wildlife photographer with a focus on insect photography, one of my mantras is: “Get a shot, any shot; refine the shot.” The preceding photo is the “record shot”; the following photos show my efforts to refine the record shot.

There were at least two males competing for the same prime location. It’s possible that all of the photos in this gallery feature the same individual, although I think it’s just as likely more than one male is shown.

Related Resources

Copyright © 2018 Walter Sanford. All rights reserved.

Twin-spotted Spiketail dragonfly (male)

May 9, 2018

A Twin-spotted Spiketail dragonfly (Cordulegaster maculata) was spotted at Occoquan Regional Park in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and “indented” hind wings.

Those who know me well are familiar with one of many “Walterisms”: “I haven’t ‘seen’ something until I have photographed it.” My rationale is two-fold: 1) A photograph verifies a sighting. 2) The detail visible in a good photograph exceeds the acuity of the human eye.

Although I’m fairly certain I’ve seen a Twin-spotted Spiketail at another location, this is the first time I was fortunate to photograph the species. Twin-spotted Spiketail is relatively uncommon in Northern Virginia.

The last two photos show what might be the same male shown in the first two photos, but it might be another male. As Mike Powell and I were photographing the first male, another dragonfly swooped in and there was either a brief aerial ballet or battle, depending upon whether the second dragonfly was a female or male. I visually tracked the first dragonfly to a new perch about 10 feet away.

When I started to move toward the new perch, Mike shouted “Don’t move, don’t move!” Mike had spotted another Twin-spotted Spiketail that landed close to the place where I spotted the first one.

We didn’t have much time to shoot photos. This Twin-spotted Spiketail and another one hooked up and they flew in wheel toward the nearby treetops. The mating process for Twin-spotted Spiketails lasts about an hour, a fact that may explain why we never saw another Twin-spotted during our photowalk.

Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.

  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | male | top view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | male | side view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | female | top view
  • Genus Cordulegaster | Cordulegaster maculata | Twin-spotted Spiketail | female | side view

Copyright © 2018 Walter Sanford. All rights reserved.

Common Whitetail (immature males)

May 7, 2018

A first-of-season Common Whitetail dragonfly (Plathemis lydia) was spotted perching on the ground near a vernal pool at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male, as indicated by his terminal appendages, brown colored abdomen, and pattern of wing spots.

30 APR 2018 | Huntley Meadows Park | Common Whitetail (immature male)

Another immature male was spotted along an informal trail at a remote location in the park.

30 APR 2018 | Huntley Meadows Park | Common Whitetail (immature male)

Young male Common Whitetails begin to develop white pruinescence that changes the color of their abdomen from brown to white, hence the common name for this species.

Sexing Common Whitetail dragonflies

For many of the common species of odonates found in Northern Virginia, I created a collection of annotated guides that illustrates how to differentiate gender by looking at terminal appendages. The difference in the pattern of wings spots for male and female Common Whitetails is sufficient to identify gender.

Copyright © 2018 Walter Sanford. All rights reserved.

Common Whitetail dragonfly (female)

May 5, 2018

Common Whitetail dragonflies (Plathemis lydia) are like bad party guests: they are among the first to arrive and last to leave. Nonetheless, it was good to see one on a day when almost no adult odonate species were observed.

30 APR 2018 | Huntley Meadows Park | Common Whitetail (female)

A Common Whitetail was spotted perching on a man-made brush pile near a vernal pool at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female, as indicated by her terminal appendages and pattern of wing spots.

30 APR 2018 | Huntley Meadows Park | Common Whitetail (female)

The “schmutz” that appears at the tip of her abdomen is probably excrement. Hey, schmutz happens!

Copyright © 2018 Walter Sanford. All rights reserved.

Blue Corporal (teneral males)

May 3, 2018

Several teneral male Blue Corporal dragonflies (Ladona deplanata) were spotted near Painted Turtle Pond during a photowalk at at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

Teneral/immature/young male Blue Corporals look similar to females of the same species. Terminal appendages can be used to differentiate gender: males have three (3) appendages; females have two (2).

Some of the ground cover is charred from a recent controlled burn at Occoquan Bay NWR.

The common name for Blue Corporal is derived from two cream-colored stripes that appear on the front of the thorax, similar to the two stripes that signify the rank of corporal in the military. As a mature male, those stripes will be partially obscured by dark blue pruinescence.

Related Resource: Blue Corporal (teneral females).

Copyright © 2018 Walter Sanford. All rights reserved.


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