Archive for June, 2014

Emerging Common Sanddragons

June 29, 2014

Two emerging Common Sanddragon dragonflies (Progomphus obscurus) were spotted on 15 June 2014 during the “Advanced Dragonfly Studies” adult class and field trip to the Patuxent Research Refuge. The field trip was led by Richard Orr, renowned expert on odonates of the mid-Atlantic region, and Stephanie Mason, Senior Naturalist, Audubon Naturalist Society.

emerge: to leave water and undergo metamorphosis into an adult; emergence is thus both from water and from exuvia Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 11593-11594). Princeton University Press. Kindle Edition.

The first two photos show a sanddragon emerging from its exuvia (plural exuviae), also known as a “cast skin.” Notice that its wings have not started expanding.

Common Sanddragon dragonfly (emerging, teneral, exuvia)

Common Sanddragon dragonfly (teneral, exuvia)

The wings, folded like accordions, then begin to fill from the base with fluid transferred from the body and fairly soon reach full length. The fluid is then pumped back into the abdomen, and it expands. Finally, the wings open up, and very soon the teneral adult flies away. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 466-468). Princeton University Press. Kindle Edition.

The last photo shows a teneral adult (upper right) and its exuvia (lower left). Since it takes approximately 30 minutes for dragonfly wings to expand, we can infer this sanddragon emerged before the other one.

Common Sanddragon dragonfly (teneral, exuvia)

Copyright © 2014 Walter Sanford. All rights reserved.

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Common Sanddragon dragonflies (mating pairs)

June 27, 2014

I spotted two mating pairs of Common Sanddragon dragonflies (Progomphus obscurus) during a photowalk at Huntley Meadows Park on 20 June 2014; both pairs are shown in the “mating wheel.”

Pairs copulate for up to 15 minutes on ground or in shrubs near water. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 4856-4857). Princeton University Press. Kindle Edition.

Both pairs began mating on the banks of the stream and moved to vegetation near the water a few minutes later.

Common Sanddragon dragonflies (mating pair, in wheel)

Photo 1. Mating pair one.

Common Sanddragon dragonflies (mating pair, in wheel)

Photo 2. Mating pair one, a few minutes later.

Common Sanddragons are a species of dragonfly formerly unknown to occur at Huntley Meadows before their discovery by Mike Powell on 17 June 2014. It’s good to know there’s a reproducing population of sanddragons at the park, as evidenced by the photos in this gallery.

Common Sanddragon dragonflies (mating pair, in wheel)

Photo 3. Mating pair two.

Common Sanddragon dragonflies (mating pair, in wheel)

Photo 4. Mating pair two, a few minutes later.

It’s fairly simple and straightforward to identify the male- and female members of a mating pair of dragonflies. All dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back: male dragonfly secondary genitalia, called hamules, are located in segments two and three (2 and 3); female genitalia in segment eight (8). Dragonflies form the mating wheel in order for their genitalia to connect during copulation.

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”). In every photo, shown above, the male dragonfly is the one using his claspers to hold the female by her head.

It is more challenging to identify single male and female dragonflies, especially when their appearance is similar. Ed Lam, author and illustrator of Damselflies of the Northeast, created the following composite image that shows how to differentiate male and female Common Sanddragons. Notice the difference in the shape of male and female hind wings: male hind wings are “indented” near the body; female hind wings are rounded. This easy-to-recognize field marker is shown most clearly in the full-size version of Photo 3, shown above.

Ed-Lam_Common-Sanddragon_male-female

Copyright © 2014 Walter Sanford. All rights reserved.

Anything but common

June 25, 2014

Common Sanddragon dragonflies (Progomphus obscurus) are anything but common.

Despite its name, this species is rare in Northern Virginia. Source Credit: Common Sanddragon, Dragonflies of Northern Virginia, by Kevin Munroe, Park Manager, Huntley Meadows Park.

Kevin goes on to cite Bull Run and Goose Creek, two streams where he has seen Common Sanddragons, and speculates they may be found at two other locations in Northern Virginia. Well, you can add a third location where sanddragons have been seen and it’s right in Kevin’s wheelhouse!

Mike Powell, a fellow amateur wildlife photographer and blogger, photographed a clubtail dragonfly at Huntley Meadows Park on 17 June 2014 that he was unable to identify. Mike’s description of the habitat where he saw the dragonfly piqued my curiosity, so I asked him to send me a photo of the unknown dragon. Turns out Mike discovered a Common Sanddragon — a new species of clubtail dragonfly for Huntley Meadows Park!

Mike volunteered to meet at the park on 20 June 2014 so that he could guide me to the location where he spotted the Common Sanddragon. After a LONG, DIFFICULT WALK to a VERY REMOTE location in the park, we spotted several sanddragons as soon as we reached our destination, including two mating pairs! The following photos show several males that I spotted during what turned out to be a very productive photowalk.

Common Sanddragon dragonfly (Progomphus obscurus)

They are usually seen along sandy shores, as their larvae are highly modified as sand burrowers. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 4833). Princeton University Press. Kindle Edition.

In this case, the sanddragons were found near sand deposits along a small stream that has carved a shallow channel in what appears to be a bed of iron-rich marine clay.

Huntley Meadows lies in a wet lowland carved by an ancient meander of the Potomac River. Source Credit: Huntley Meadows Park home page, Fairfax County Park Authority.

Common Sanddragon dragonfly (Progomphus obscurus)

Common Sanddragon dragonfly (Progomphus obscurus)

Common Sanddragon dragonfly (Progomphus obscurus)

The last photo in the set shows a male perching in a pose similar to the “obelisk position,” used by some dragonflies as a method of thermoregulation. Although sanddragons obelisk, especially at midday, the pose of this male sanddragon is probably intended to both attract females and communicate to other males, “This is my territory.”

Common Sanddragon dragonfly (Progomphus obscurus)

Editor’s Note: Please stay tuned for several upcoming posts featuring more photos of Common Sanddragon dragonflies, including two mating pairs, and two emergent sanddragons and their exuviaea (cast skins) — in short, a photo-documentary of most of the sanddragon life cycle!

Copyright © 2014 Walter Sanford. All rights reserved.

Common Whitetail dragonflies (immature males)

June 23, 2014

This post features more photos of Common Whitetail dragonflies (Plathemis Lydia) spotted on 18 May 2014 in the meadow east of the observation tower at Huntley Meadows Park.

The dragonflies shown below are immature males, as indicated by their coloration, pattern of wing spots, and terminal appendages. As mature adults, the abdomen of these male dragonflies will be covered by white pruinescence, hence the common name, “Common Whitetail.”

Common Whitetail dragonfly (immature male)

Common Whitetail dragonfly (immature male)

Common Whitetail dragonfly (immature male)

Common Whitetail dragonfly (immature male)

I love a good head-tilt

Common Whitetail dragonfly (immature male)

Common Whitetail dragonfly (immature male)

Copyright © 2014 Walter Sanford. All rights reserved.

Common Whitetail dragonflies (females)

June 21, 2014

On 18 May 2014, I saw lots of Common Whitetail dragonflies (Plathemis lydia) in the meadow east of the observation tower at Huntley Meadows Park.

The dragonflies shown below are females, as indicated by their coloration, pattern of wing spots, and terminal appendages.

Common Whitetail dragonfly (female)

Common Whitetail dragonfly (female)

Common Whitetail dragonfly (female)

Copyright © 2014 Walter Sanford. All rights reserved.

Swamp Darner dragonfly (female, oviposition)

June 19, 2014

I spotted a Swamp Darner dragonfly (Epiaeschna heros) during a photowalk at Huntley Meadows Park on 02 June 2014. This individual is a female, shown laying eggs (oviposition) in mud alongside a vernal pool.

Richard Orr, renowned expert on odonates of the mid-Atlantic region, shared several interesting factoids about Darners and Swamp Darners during “Advanced Dragonfly Studies,” a recent Audubon Naturalist Society Adult Class and Field Trip:

  • Petaltails (Petaluridae) were once thought to be the oldest family of dragonflies; recent genetic studies have shown that Darners (Aeshnidae) are the most primitive family.
  • Darners have the most complex compound eyes in the insect world.
  • Swamp Darner eggs can survive for up to a year without water, in case the vernal pool (where the female laid her eggs) evaporates during summer.

All female damselflies and many female dragonflies, especially Aeschnidae, have an ovipositor that is used to puncture aquatic plants, logs, wet mud, etc.; eggs are placed singly in the puncture. The ovipositor is clearly visible in all of the following photos.

Swamp Darner dragonfly (female, oviposition)

Swamp Darner dragonfly (female, oviposition)

Swamp Darner dragonfly (female, oviposition)

Swamp Darner dragonfly (female, oviposition)

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

See also Swamp Darner Ovipositing in Rotting Log (NJ, USA), an excellent YouTube video published on June 5, 2014, shot from the edge of a vernal pool located in New Jersey.

Copyright © 2014 Walter Sanford. All rights reserved.

Fragile Forktail damselflies

June 17, 2014

I spotted several Fragile Forktail damselflies (Ischnura posita) during a photowalk at Huntley Meadows Park on 21 April 2014. The damselflies were the first “home grown” odonates I saw in 2014.

Fragile Forktail damselflies are black and either light green (males) or light blue (females and immature males). The top of the thorax is black with two distinctive green- or  blue exclamation points.

The following individuals are females; their gender was kindly verified by two members of the Northeast Odonata Facebook group.

Its sex is female. The abdomen looks proportionately thick throughout, and on the full-size image, you can make out the simple cerci at the tip. I’m not sure males would ever show this much pruinosity either. Source Credit: Benjamin A. Coulter, Northeast Odonata Facebook group.

Fragile Forktail damselfly (immature female)

I would call it fully mature too. The females don’t get any brighter as they get older, they just get more pruinose (chalky blue-gray) and that process has started on yours. Source Credit: Chris Hill, Northeast Odonata Facebook group.

Fragile Forktail damselfly (immature female)

The following individual is a male, as indicated by its green coloration. This specimen was spotted on 27 April 2014 along the gravel road between the terminus of the Hike-Bike Trail and the new observation platform.

Fragile Forktail damselfly (male)

Copyright © 2014 Walter Sanford. All rights reserved.

Common Five-lined Skink (eating a spider)

June 15, 2014

I spotted a Common Five-lined Skink (Plestiodon fasciatus) eating a spider during a photowalk along the boardwalk at Huntley Meadows Park on 18 May 2014. The spider appears to be a Wolf spider (Family Lycosidae).

Common Five-lined Skink (adult, eating a spider)

Common Five-lined Skink (adult, eating a spider)

Common Five-lined Skink (adult, eating a spider)

Copyright © 2014 Walter Sanford. All rights reserved.

Eastern Pondhawk dragonflies (females)

June 13, 2014

This post features photos of several Eastern Pondhawk dragonflies (Erythemis simplicicollis) spotted during a photowalk at Huntley Meadows Park on 23 May 2014. These individuals are females, as indicated by their green coloration and white terminal appendages.

Eastern Pondhawk dragonfly (female)

Eastern Pondhawk dragonflies perch either near- or on the ground. Like many species of dragonflies in the Skimmer family, the Eastern Pondhawk usually perches on four of six legs, with the two front legs curled around its head.

Eastern Pondhawk dragonfly (female)

Voracious predator, especially females, eating odonates of all kinds their own size and smaller, … Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 10223-10224). Princeton University Press. Kindle Edition.

Dragonflies use their front legs like a “basket” to catch prey in mid-air. Look closely at the full-size version of the following photo, showing one of the females eating some type of winged insect cradled in her front legs.

Eastern Pondhawk dragonfly (female, eating an insect)

Related Resources:

Copyright © 2014 Walter Sanford. All rights reserved.

Great Spangled Fritillary butterfly

June 11, 2014

Great Spangled Fritillary butterfly (Speyeria cybele)

I spotted a Great Spangled Fritillary butterfly (Speyeria cybele) during a photowalk at Huntley Meadows Park on 06 June 2014. This individual is feeding on mineral salts from the gravel road on which it is perching, as shown in the following photo.

Great Spangled Fritillary butterfly (Speyeria cybele)

Finally, a look at the underside of its wings …

Great Spangled Fritillary butterfly (Speyeria cybele)

Copyright © 2014 Walter Sanford. All rights reserved.


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