Archive for October, 2016

Sexing Common Green Darner dragonflies

October 30, 2016

Several field markers can be used to identify the gender of female and male Common Green Darner dragonflies (Anax junius).

Female

The following individual, spotted at Huntley Meadows Park, is a female. Female dragonflies have a pair of cerci (superior appendages) that have little or no function. The cerci (sing. cercus) of female Common Green Darners look like almonds, both in color and shape.

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

Two more field markers verify this specimen is female.

Note the brown stripe extending onto abdominal segment 2. Segment 2 [S2] is typically all pale on males. Also viewing at full resolution, the rear margin of the occiput is not straight. Females have blunt dark colored “teeth” back there which makes the margin look wavy. Source Credit: Ed Lam, author and illustrator of Damselflies of the Northeast, Northeast Odonata Facebook group.

Male

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 cerci of male Common Green Darners are slightly darker in color and somewhat thicker and more rounded than the cerci of females of the same species. There are points at the tips of the two male cerci, as shown clearly in the full-size version of the following photo; female cerci are pointless, both literally and figuratively.

Male Common Green Darners have a very short epiproct that is used to grip the “teeth” on the back of head of females of the same species.

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

The individual in the preceding image is an immature male, as indicated by the purple coloration on his abdomen. As a mature male, his abdomen will be partially covered by blue pruinescence like the one shown below.

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

  • Genus Anax | Anax junius | Common Green Darner | female | top view
  • Genus Anax | Anax junius | Common Green Darner | female | side view
  • Genus Anax | Anax junius | Common Green Darner | male | top view
  • Genus Anax | Anax junius | Common Green Darner | male | side view

Compare and contrast the cerci of female and male Common Green Darners by viewing the full-size versions of the preceding top views for both sexes and Ed Lam’s excellent composite image, shown below.

ed-lam_cgd_male-vs-female

Composite image used with permission from Ed Lam.

Copyright © 2016 Walter Sanford. All rights reserved.

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Painted Skimmer dragonfly (female)

October 28, 2016

As I was reviewing my photo library in search of candidates for the “Top 10 Photos of 2016” catalog, I stumbled across an unpublished photo of one of my favorite species of odonates.

Turns out there are lots of good photos that weren’t published for one reason or another. Now that ode-hunting season is undeniably winding down, more of these photos will be published during the “off-season.”

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

31 MAY 2016 | Huntley Meadows Park | Painted Skimmer (female)

A Painted Skimmer dragonfly (Libellula semifasciata) was spotted near a vernal pool in a remote location at Huntley Meadows Park. This individual is a female, as indicated by her terminal appendages.

Copyright © 2016 Walter Sanford. All rights reserved.

Eastern Pondhawk dragonflies (mating pair)

October 26, 2016
A mating pair of Eastern Pondhawk dragonflies (Erythemis simplicicollis) spotted at Hidden Pond, Meadowood Recreation Area. Fairfax County, Virginia USA. This pair is "in wheel." The female is infested with water mites.

21 JUN 2016 | MRA | Eastern Pondhawk (mating pair, “in wheel”)

A mating pair of Eastern Pondhawk dragonflies (Erythemis simplicicollis) was spotted along the earthen dam at Hidden PondMeadowood Recreation Area. This pair is “in wheel“: the male is on the upper-right; the female is on the lower-left.

Eastern Pondhawks mate quickly.

Copulation brief (averages 20 sec) and aerial, may be followed by resting period. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 10228). Princeton University Press. Kindle Edition.

The mating pair was in wheel when they landed. I was able to shoot one photo before they finished copulating!

Look closely at the full-size version of the preceding photo. Notice the female is infested with parasitic water mites on the underside of her abdomen.

Copyright © 2016 Walter Sanford. All rights reserved.

Slender Bluet damselflies (mating pair)

October 24, 2016

A mating pair of Slender Bluet damselflies (Enallagma traviatum) was spotted during a photowalk around Mulligan Pond at Jackson Miles Abbott Wetland Refuge (JMAWR). This pair is “in heart“: the male is on top; the female is on the bottom.

A mating pair of Slender Bluet damselflies (Enallagma traviatum) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This pair is "in heart."

14 JUN 2016 | JMAWR | Slender Bluet (mating pair, “in heart”)

This mating pair is my first confirmed sighting of Slender Bluet damselfly. Enallagma traviatum is classified as a member of Family Coenagrionidae (Narrow-winged Damselflies). The Genus Enallagma (American Bluets) is one of three genera in the Family Coenagrionidae that are common in Northern Virginia.

Notice the large postocular spots spots separated by a straight line that look like a dumbbell. The spots are darker blue for males; lighter blue for females. This pattern of post ocular spots may be used to differentiate Slender Bluet from the somewhat similar looking Blue-fronted Dancer damselflies (Argia apicalis): the eye spots are smaller and the straight line is missing for Blue-fronted Dancer.

It’s helpful to get shots of mating pairs of damselflies, especially “in tandem,” since males and females of the same species can look quite different. The excellent high-resolution digital scans by Gayle and Jeanelle Strickland, listed under “Related Resources” (below), provide clear views of male and female Slender Bluet damselflies.

Related Resources:

Copyright © 2016 Walter Sanford. All rights reserved.

Headfirst

October 22, 2016

Common Green Darner dragonfly (Anax junius) landed a few feet to my left as I was looking for Russet-tipped Clubtail dragonflies during a photowalk around Mulligan Pond at Jackson Miles Abbott Wetland Refuge (JMAWR).

Almost immediately, I realized the Common Green Darner was eating a smaller female Autumn Meadowhawk dragonfly (Sympetrum vicinum).

A Common Green Darner dragonfly (Anax junius) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male, eating a female Autumn Meadowhawk dragonfly (Sympetrum vicinum).

16 OCT 2016 | JMAWR | Common Green Darner (male, eating prey)

Notice the Common Green Darner is eating the Autumn Meadowhawk headfirst, the fastest way for the predator to immobilize its prey.

A Common Green Darner dragonfly (Anax junius) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male, eating a female Autumn Meadowhawk dragonfly (Sympetrum vicinum).

16 OCT 2016 | JMAWR | Common Green Darner (male, eating prey)

The Common Green Darner is an immature- to young male, as indicated by his coloration and terminal appendages. As a mature male, his abdomen will be partially covered by blue pruinescence.

A Common Green Darner dragonfly (Anax junius) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male, eating a female Autumn Meadowhawk dragonfly (Sympetrum vicinum).

16 OCT 2016 | JMAWR | Common Green Darner (male, eating prey)

Copyright © 2016 Walter Sanford. All rights reserved.

Another sighting of Russet-tipped Clubtail

October 20, 2016

It was my good fortune to see another Russet-tipped Clubtail dragonfly (Stylurus plagiatus) on 03 October 2016 during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR).

This one was by far the most challenging to spot/rewarding to find because the dragonfly was perching high in a cedar tree where it was well camouflaged.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male. [*]

03 OCT 2016 | JMAWR | Russet-tipped Clubtail (male)

This individual is a male, as indicated by the large russet-colored club at the end of his abdomen, and his terminal appendages. Notice the epiproct is a large “plate” that spans both cerci, as shown in the full-size version of the following photo.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male. [Good view of terminal appendages.]

03 OCT 2016 | JMAWR | Russet-tipped Clubtail (male)

I love a good head-tilt, as shown in the next photo.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

03 OCT 2016 | JMAWR | Russet-tipped Clubtail (male)

I like the way the coloration of the male Russet-tipped Clubtail complements the color palette of the background in all of the photos.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male. [Good view of terminal appendages.]

03 OCT 2016 | JMAWR | Russet-tipped Clubtail (male)

Copyright © 2016 Walter Sanford. All rights reserved.

Shadow Darner dragonfly (female)

October 18, 2016

A Shadow Darner dragonfly (Aeshna umbrosa) was spotted during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR).

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph.

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

This individual is a mature female, as indicated by her coloration, rounded hindwings (near abdomen), and terminal appendages. Female Shadow Darners are polymorphic; this one is a female heteromorph, as indicated by her brown eyes and duller coloration than males of the same species.

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph.

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

The following annotated image illustrates some parts of the reproductive anatomy of a female Shadow Darner dragonfly, including an ovipositor for egg-laying and two styli (sing. stylus), structures that serve as sensors in egg positioning.

A Shadow Darner dragonfly (Aeshna umbrosa) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a female heteromorph. [Good view of ovipositor/styli.]

14 OCT 2016 | JMAWR | Shadow Darner (female heteromorph)

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

Both female and male Shadow Darners have two long, petal-like cerci (sing. cercus). Notice the female (shown above) is missing both cerci.

[Female] Cerci rounded at tip, longer than S9–10, usually broken off at maturitySource Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 4604). Princeton University Press. Kindle Edition.

In contrast, the following male has both cerci and an epiproct; the three terminal appendages are collectively called “claspers.” Claspers are used to grab and hold female damselflies during mating.

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

Related Resources: Scanned digital images from Western Odonata Scans in Life.

  • Shadow Darner | Aeshna umbrosaheteromorph female
  • Shadow Darner | Aeshna umbrosaheteromorph female (note very tattered wings of this old individual)
  • Shadow Darner | Aeshna umbrosaandromorph female
  • Shadow Darner | Aeshna umbrosamale (typical “A. u. umbrosa” with small green abdominal spots but nowhere near the range of that subspecies!)

Copyright © 2016 Walter Sanford. All rights reserved.

Black Saddlebags dragonfly (male)

October 16, 2016

When I’m walking in/out of the wildlife watching parks that I like to visit some people ask, “Did you see/take photographs of anything good?” In my experience, their idea of “anything good” is either birds or large mammals. But if you take the time to look closely at the natural world then you will see smaller things that are easy to overlook, such as dragonflies and damselflies. And if you’re lucky, one of these magnificent animals will let you get close enough to see their breathtaking beauty!

A Black Saddlebags dragonfly (Tramea lacerata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. [*]

10 OCT 2016 | Huntley Meadows Park | Black Saddlebags (male)

Black Saddlebags dragonfly (Tramea lacerata) was spotted near a vernal pool in a remote location at Huntley Meadows Park. This individual is a male, as indicated by his terminal appendages.

Copyright © 2016 Walter Sanford. All rights reserved.

Another Russet-tipped Clubtail

October 14, 2016

I was eager to see another Russet-tipped Clubtail dragonfly (Stylurus plagiatus) after I spotted one on 22 September 2016 during a photowalk at Mulligan PondJackson Miles Abbott Wetland Refuge (JMAWR).

A male Russet-tipped Clubtail was observed on 25 September 2016 at JMAWR, but it was only a fleeting glimpse. When I spotted him, he was flitting around looking for a perch — after two “touch-and-gos” he flew toward the trees in the distance and I never saw him again.

Another Russet-tipped Clubtail was spotted on 27 September 2016 that was more cooperative. This individual is a male, as indicated by the large russet-colored club at the end of his abdomen, and his terminal appendages.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | JMAWR | Russet-tipped Clubtail (male)

Notice this male has tattered wings; the one spotted on 22 September does not. Facing forward, there’s a nick in the lower-left hindwing (above), and a chunk is missing from the upper-right forewing (below). Although this post is entitled Another Russet-tipped Clubtail, this male could be the same one seen on either the 22nd or the 25th with wing damage sustained during the interval between photowalks.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | JMAWR | Russet-tipped Clubtail (male)

I love a good head-tilt, as shown in the preceding photo. But wait, there’s more to love — the hint of fall in the foliage in all of the photos.

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | JMAWR | Russet-tipped Clubtail (male)

Also notice all of the photos in this gallery show excrement extending from the tip of the abdomen. I’m a paparazzi who likes to photograph odonates “going about their usual life routines,” including doing their business. Hey, life happens!

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | JMAWR | Russet-tipped Clubtail (male)

A Russet-tipped Clubtail dragonfly (Stylurus plagiatus) spotted at Mulligan Pond, Jackson Miles Abbott Wetland Refuge, Fairfax County, Virginia USA. This individual is a male.

27 SEP 2016 | JMAWR | Russet-tipped Clubtail (male)

Copyright © 2016 Walter Sanford. All rights reserved.

Widow Skimmer dragonfly (female)

October 12, 2016

Widow Skimmer dragonfly (Libellula luctuosa) was spotted at Mason Neck West Park, Fairfax County, Virginia USA. This individual is a female, as indicated by the pattern of wing spots and her terminal appendages.

I was able to take one shot of the dragonfly as seen from a typical viewpoint before she moved to a perch located slightly above my head. Making lemonade from lemons, I continued to take photos. In retrospect, I realized the two shots from a ventral viewpoint turned out to be more visually interesting than the dorsal view.

I love a good head-tilt!

Copyright © 2016 Walter Sanford. All rights reserved.


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