Archive for August, 2012

Common Ribbonsnake

August 28, 2012

A Common Ribbonsnake (Thamnophis sauritus sauritus) spotted on a bush beyond the observation tower in the central wetland area at Huntley Meadows Park. Photo 1 is entitled, “Open your mouth wide and say, ‘Ahhh!'” I’m not sure whether the snake was yawning or trying to intimidate me.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

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Common Green Darner dragonfly (mating pair, in tandem, oviposition)

August 26, 2012

The following photos show a mating pair of Common Green Darner dragonflies (Anax junius) spotted at Huntley Meadows Park. This pair is in tandem: The male is shown on the left; the female on the right. The female is laying eggs on the surface of underwater plants (epiphytic ovipostion). The Common Green Darner dragonfly is the only North American darner that usually oviposits in tandem. Notice the difference in color of the pterostigmas for the male and female.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Eastern Tiger Swallowtail butterfly (female)

August 24, 2012

An Eastern Tiger Swallowtail butterfly (Papilio glaucus) feeding on Common Buttonbush (Cephalanthus occidentalis) in the central wetland area at Huntley Meadows Park. This individual is a female, as indicated by the blue and orange markings on the lower edge of its hindwings. Tiger Swallowtail is the State Insect of Virginia.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Blue Dasher dragonfly (male) redux

August 22, 2012

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted along the boardwalk that goes through the central wetland area at Huntley Meadows Park. This individual is a male, as indicated by its blue coloration and the terminal appendages at the end of its abdomen. Look closely and you will see some of the ommatidia, that is, the facets in the dragonfly’s compound eyes!

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Some dragonflies, such as the 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 dragonfly perched in the obelisk position casts a very small shadow, as shown in Photo 2 in the preceding gallery.

Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Slaty Skimmer dragonfly (immature female)

August 20, 2012

The following photos show a dragonfly spotted during a photowalk along the “Hike-Bike Trail” at Huntley Meadows Park. This individual is a female, as indicated the terminal appendages at the end of its abdomen. It is either a Slaty Skimmer or Great Blue Skimmer, both of which are somewhat similar in appearance. A couple of definitive characters aren’t clearly visible in these photos.

  1. A black triangle below the base of the front wing is a good way to separate the species: Slaty Skimmers have it; Great Blue Skimmers do not.
  2. Face color can be used too: the faces of Slaty females are reddish-brown; the faces of Great Blue females are white.

Conclusion: Since this individual’s femora are mostly dark colored, it is an immature female Slaty Skimmer dragonfly (Libellula incesta).

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Related Resources:

  • Slaty Skimmer – “The legs are black with brown only at their extreme bases.”
  • Great Blue Skimmers – “The femora are pale over their basal half with the remaining length, tibiae and tarsi black.”

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

  • Genus Libellula | Libellula incesta | Slaty Skimmer | male | top view
  • Genus Libellula | Libellula incesta | Slaty Skimmer | male | side view
  • Genus Libellula | Libellula vibrans | Great Blue Skimmer | female | top view
  • Genus Libellula | Libellula vibrans | Great Blue Skimmer | female | side view

Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Eastern Gartersnake

August 18, 2012

An Eastern Gartersnake (Thamnophis sirtalis sirtalis) spotted in the woods along the path between the boardwalk and the observation tower at Huntley Meadows Park. According to the Virginia Herpetological Society, the Eastern Gartersnake can be differentiated from the Common Ribbonsnake by the presence of “dark vertical lines on the margins of the supralabial scales.”

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Louisa,” a good friend and fellow Project Noah spotter, is shown photographing the same snake (see Photos 5-6 in the preceding gallery).

Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Eastern Tiger Swallowtail butterfly (female, dark morph)

August 16, 2012

An Eastern Tiger Swallowtail butterfly (Papilio glaucus) spotted during a photowalk through the “Wildlife Sanctuary,” one of seven small parks in the community of Hollin Hills, Fairfax County, Virginia USA.

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This individual is a dark morph female. “Females are dimorphic. The yellow morph differs from the male in having a blue postmedian area on the dorsal hind wing. In the dark morph, the areas that are normally yellow are replaced with dark gray or black.” Source Credit: Wikipedia

Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Great Blue Skimmer dragonfly (female)

August 14, 2012

A Great Blue Skimmer dragonfly (Libellula vibrans) spotted along the “Hike-Bike Trail” at Huntley Meadows Park. This individual is a female as indicated by its coloration, and by the flanges beneath its eighth abdominal segment (used to scoop and hold a few drops of water during oviposition). Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

The femora are pale over their basal half with the remaining length, tibiae and tarsi black. Source Credit: Great Blue Skimmer, Odonata Central.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Eastern Pondhawk dragonflies (females)

August 12, 2012

The following photographs show a couple of female Eastern Pondhawk dragonflies (Erythemis simplicicollis) spotted in a meadow located at least 100 yards from the central wetland area at Huntley Meadows Park.

Notice the subgenital plate, a black “shark fin” located beneath segment eight of the abdomen.

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.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com

Variegated Fritillary butterfly

August 10, 2012

A Variegated Fritillary butterfly (Euptoieta claudia), a beautiful medium-sized butterfly, spotted during a photowalk through the Children’s Garden at Hollin Meadows Science and Math Focus School.

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Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com


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