Archive for May, 2015

Twelve-spotted Skimmer dragonfly terminal appendages

May 31, 2015

Twelve-spotted Skimmer (Libellula pulchella) is a member of the Skimmer Family of dragonflies that is spotted during the summer months at many water bodies in the mid-Atlantic United States, such as the wetlands at Huntley Meadows Park (HMP).

Twelve-spotted Skimmers display sexual dimorphism; terminal appendages may be used to differentiate immature males from females.

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”).

The preceding individual is a young male, as indicated by the white partial pruinescence covering his abdomen. In contrast, the abdomen of the following mature male is completely white.

Female dragonflies have a pair of cerci (superior appendages) that have little or no function.

Related Resources: Odonate Terminal Appendages.

Copyright © 2015 Walter Sanford. All rights reserved.

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Twelve-spotted Skimmer dragonfly (young male)

May 29, 2015

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) was spotted near a vernal pool at Huntley Meadows Park (HMP). This individual is a young adult male, as indicated by its partial pruinescence, distinctive pattern of wing spots, and terminal appendages. As a mature adult male, its abdomen will be completely covered by white pruinescence.

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

22 MAY 2015 | HMP | Twelve-spotted Skimmer (young male)

Among dragonflies that exhibit sexual dimorphism, such as Twelve-spotted Skimmers, immature/young males and females are similar in appearance. The pattern of wing spots is a key field marker for identification of Twelve-spotted Skimmer males and females, in addition to differences in their terminal appendages.

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

22 MAY 2015 | HMP | Twelve-spotted Skimmer (young male)

Editor’s Note: With no disrespect intended toward Kevin Munroe, whom I admire and respect, I feel compelled to point out an error on Kevin’s Twelve-spotted Skimmer page. In the lower-right corner of page 1, an immature male is misidentified as a female. Believe me when I tell you Kevin’s expertise far exceeds mine, but hey, only someone like me with a fixation on odonate terminal appendages would have recognized the immature male’s claspers!

Copyright © 2015 Walter Sanford. All rights reserved.

Twelve-spotted Skimmer dragonfly (female)

May 27, 2015

Twelve-spotted Skimmer dragonfly (Libellula pulchella) was spotted perched in a small meadow near a vernal pool at Huntley Meadows Park (HMP). This individual is a female, as indicated by its coloration and terminal appendages.

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

22 MAY 2015 | HMP | Twelve-spotted Skimmer (female)

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

22 MAY 2015 | HMP | Twelve-spotted Skimmer (female)

A Twelve-spotted Skimmer dragonfly (Libellula pulchella) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

22 MAY 2015 | HMP | Twelve-spotted Skimmer (female)

Female Twelve-spotted Skimmer dragonflies appear very similar to female Common Whitetails.

Although males quite different, female Common Whitetail poses identification problem, as she has same 12 wing spots. In addition to being distinctly smaller, female Whitetail has series of yellowish-whitish spots not contacting edge of each abdominal segment, whereas female Twelve-spotted has continuous parallel yellow stripes on either edge of abdomen. In side view of thorax, female Whitetail has additional yellow dot in front of anterior yellow stripe, lacking in Twelve-spotted. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 9017-9021). Princeton University Press. Kindle Edition.

In summary, the key field marker that may be used to differentiate female Twelve-spotted Skimmers from female Common Whitetail Skimmers is the stripe along both sides of their abdomens: Twelve-spotted Skimmers have two stripes of continuous rectangles; Common Whitetails have two stripes made of separated triangles.

Common Whitetail dragonfly (Plathemis lydia) was spotted about a month earlier at the same location. This individual is a female, as indicated by its coloration, pattern of wing spots, and terminal appendages.

Look closely at the pattern of wing spots for the female Common Whitetail, in particular, the middle spots on each wing. Notice the shape of each middle spot forms a “spike” that points toward the body of the dragonfly. In contrast, the middle wing spots for female Twelve-spotted Skimmer aren’t “spiked.” An excellent blog post by DSA member Jim Johnson, entitled “ID Challenge #3 Answer,” illustrates the difference in the pattern of wing spots for these two species (using proper terminology).

A Common Whitetail dragonfly (Plathemis lydia) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

27 APR 2015 | Huntley Meadows Park | Common Whitetail (female)

Common Whitetail dragonflies, including both males and females, are in fact quite common. In my experience, female Twelve-spotted Skimmers are an uncommon spotting. I wonder how many Twelve-spotted Skimmer females are overlooked by this sort of dismissive thinking: “Nothing to see here folks, it’s just another female Common Whitetail. Move along.”

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

  • Genus Libellula | Libellula pulchella | Twelve-spotted Skimmer | female | top view
  • Genus Libellula | Libellula pulchella | Twelve-spotted Skimmer | female | side view
  • Genus Libellula | Libellula lydia [sic] | Common Whitetail | female | top view

Copyright © 2015 Walter Sanford. All rights reserved.

Blue Dasher dragonflies (immature males)

May 25, 2015

Blue Dasher dragonflies (Pachydiplax longipennis) display sexual dimorphism; terminal appendages may be used to differentiate immature males from females.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

14 MAY 2015 | Huntley Meadows Park | Blue Dasher (immature male)

This individual is an immature male, as indicated by its red eye color, blue partial pruinescence, and terminal appendages. When male Blue Dashers mature, their eyes are blue-green and their abdomen is completely blue except for the black tip.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

14 MAY 2015 | Huntley Meadows Park | Blue Dasher (immature male)

Some dragonflies, such as Blue Dasher, regulate their body temperature by perching in the “obelisk position”: the tip of the dragonfly’s abdomen is pointed toward the Sun, minimizing the surface area of the body exposed to direct heating by the Sun’s rays, thereby avoiding overheating.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

14 MAY 2015 | Huntley Meadows Park | Blue Dasher (immature male)

Another immature male was spotted at the same location about a week later.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male with a malformed wing.

22 MAY 2015 | Huntley Meadows Park | Blue Dasher (immature male)

Did you notice this individual has a malformed wing? A lot can go wrong when a dragonfly metamorphoses from a larva to an adult!

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male with a malformed wing.

22 MAY 2015 | Huntley Meadows Park | Blue Dasher (immature male)

Copyright © 2015 Walter Sanford. All rights reserved.

Blue Dasher dragonfly (teneral female)

May 23, 2015

Blue Dasher dragonfly (Pachydiplax longipennis) was spotted during a photowalk at Huntley Meadows Park on 20 May 2015.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a teneral female.

20 MAY 2015 | Huntley Meadows Park | Blue Dasher (teneral female)

This individual is a teneral female, as indicated by its coloration and terminal appendages. Notice the fragile appearance of her wings.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a teneral female.

20 MAY 2015 | Huntley Meadows Park | Blue Dasher (teneral female)

She was sheltering close to the ground in the “drowned forest,” just beyond the end of the boardwalk.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a teneral female.

20 MAY 2015 | Huntley Meadows Park | Blue Dasher (teneral female)

Contrast the appearance of the teneral female shown above with the following slightly more mature female spotted on the same day at a different location.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

20 MAY 2015 | Huntley Meadows Park | Blue Dasher (female)

Notice that her eye coloration is changing from red to blue as she matures. Also notice she is perching a few feet above the ground/water, the preferred height for Blue Dashers.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

20 MAY 2015 | Huntley Meadows Park | Blue Dasher (female)

Copyright © 2015 Walter Sanford. All rights reserved.

Blue Flag Iris

May 21, 2015

Man does not live by odonate alone. There, I said it. You may be thinking, “Oh no he didn’t. Blasphemer! Heretic!” I guess sometimes I need to channel my inner Cindy Dyer.

Blue Flag Iris (Iris virginica) is a perennial wildflower that can be found near the end of the boardwalk at Huntley Meadows Park, among many places at the park.

Blue Flag Iris (Iris virginica) spotted at Huntley Meadows Park, Fairfax County, Virginia USA.

14 MAY 2015 | Huntley Meadows Park | Blue Flag Iris (Iris virginica)

Iris was one of my mother’s favorite flowers, occupying a large part of her garden at the home where I grew up in Alexandria, Virginia. A belated but no less sincere “Happy Mother’s Day!” to you, Mom! Always thinking of you. Rest in peace.

Blue Flag Iris (Iris virginica) spotted at Huntley Meadows Park, Fairfax County, Virginia USA.

14 MAY 2015 | Huntley Meadows Park | Blue Flag Iris (Iris virginica)

Copyright © 2015 Walter Sanford. All rights reserved.

What’s my motivation?

May 19, 2015

True confession: I’ve struggled to stay motivated recently. The little voice inside my head kept asking, “Why do you endure long, difficult walks through chigger- and tick-infested vegetation, thorny vines, blood-thirsty mosquitos, hot and humid weather — all in pursuit of dragonflies and damselflies?”

Then I was reminded of the answer to my question: Sometimes Mother Nature gives me a glimpse of her awesome beauty. I enjoy sharing photographs of my good fortune, and I enjoy the opportunity for informal science education provided by my wildlife photography. I hope followers of my photoblog enjoy both looking at the photos and reading the related text!

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

I spotted a single Painted Skimmer dragonfly (Libellula semifasciata) perching in a small meadow near a vernal pool.

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

This individual is a female, as indicated by its terminal appendages. Female Painted Skimmers have a pair of flanges beneath their eighth abdominal segment that are used to scoop and hold a few drops of water when laying eggs (oviposition), hence the family name “Skimmer.” Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

I’m especially fond of head-tilts in which the individual seems to display some of its personality.

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

I worked the shot until my stunningly beautiful model …

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

… decided the photoshoot was finished and flew high into the nearby trees.

A Painted Skimmer dragonfly (Libellula semifasciata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

14 MAY 2015 | Huntley Meadows Park | Painted Skimmer (female)

Please look at the full-size version of the preceding photos in order to see the exquisite coloration of this dragonfly.

Copyright © 2015 Walter Sanford. All rights reserved.

Swamp Darner dragonfly (female)

May 17, 2015

Dragonflies are classified as either “fliers” or “perchers,” based upon their feeding habits. Swamp Darner dragonflies (Epiaeschna heros) are fliers; it is uncommon to see them perching.

A Swamp Darner dragonfly (Epiaeschna heros) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

15 MAY 2015 | Huntley Meadows Park | Swamp Darner (female)

This individual is a female, as indicated by her terminal appendages. She was perching near a vernal pool, probably resting after egg-laying (oviposition).

A Swamp Darner dragonfly (Epiaeschna heros) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

15 MAY 2015 | Huntley Meadows Park | Swamp Darner (female)

Please look at the full-size version of both photos in order to see the exquisite coloration of this dragonfly.

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

  • Genus Epiaeschna | Epiaeschna heros | Swamp Darner | female | top view
  • Genus Epiaeschna | Epiaeschna heros | Swamp Darner | female | side view
  • Genus Epiaeschna | Epiaeschna heros | Swamp Darner | male | top view
  • Genus Epiaeschna | Epiaeschna heros | Swamp Darner | male | side view

Copyright © 2015 Walter Sanford. All rights reserved.

Phishing snakes

May 15, 2015

The following photos show one or more Northern Watersnakes (Nerodia sipedon sipedon) spotted during photowalks along the boardwalk in the hemi-marsh at Huntley Meadows Park in mid-September 2014.

What do you see when you look at the following photos? I think most people would say they see a snake lying on a log, sunning itself. Now look more closely at the full-size versions of each photo — there’s more than meets the eye!

Several fish are visible in the water. Notice most of the fish are located under the log. Like all animals, fish need food and shelter in order to survive. Many species of fish prefer to find a holding place that provides shelter, such as the log, and look for food as it passes their safe spot.

Northern Watersnake (Nerodia sipedon sipedon)

15 September 2014

Over a period lasting several days, I observed one or more snakes hunting fish at the same location. The snake would lie perfectly still on top of the log; as soon as the fish were lulled into a false sense of security, the snake would slip into the water suddenly and snag an unsuspecting fish. The same thing happened again and again, so I’m guessing the snake(s) figured out a good strategy for finding food easily.

Northern Watersnake (Nerodia sipedon sipedon)

15 September 2014

A few days later, there were noticeably fewer fish hiding below the log. Can you say “overfishing?”

Northern Watersnake (Nerodia sipedon sipedon)

19 September 2014

Copyright © 2015 Walter Sanford. All rights reserved.

A Southern Fortnight, Part 3 – Southern Spreadwing damselfly (male)

May 13, 2015

The Backstory: A Southern Fortnight

For the first two weeks during May 2015, Southern Spreadwing damselflies (Lestes australis) were observed at a vernal pool and nearby drainage ditch in the forest at Huntley Meadows Park. I spotted approximately six males and several females during the fortnight. Their sudden disappearance seemed to coincide with a population explosion of Eastern Pondhawk dragonflies (Erythemis simplicicollis) in mid-May. Eastern Pondhawks, especially females, are voracious predators with a penchant for preying upon damselflies.


Southern Spreadwing damselfly (Lestes australis) was spotted perching on vegetation in a vernal pool at Huntley Meadows Park. This individual is a male, as indicated by its coloration and terminal appendages.

Copyright © 2015 Walter Sanford. All rights reserved.


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