Posts Tagged ‘pterostigma’

Denizen of the seep

July 8, 2019

An Ebony Jewelwing damselfly (Calopteryx maculata) was spotted near a forest seep located in Occoquan Regional Park, Fairfax County, Virginia USA. This individual is a male, as indicated by the absence of white pterostigma — a field mark used to identify females of the same species.

Look for Ebony Jewelwing beginning in late-May/early-June along almost any small- to mid-size forest stream in Northern Virginia (USA).

Ebony Jewelwing is a member of Family Calopterygidae (Broad-winged Damselflies). American Rubyspot (Hetaerina americana) is the only other species of Broad-winged Damselfly found in Northern Virginia.

Adult flight period

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for C. maculata is from April 27 to October 06. The species is classified as common. Its habitat is “streams, rivers.”

Copyright © 2019 Walter Sanford. All rights reserved.

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Last man standing

July 14, 2018

One, possibly two Sable Clubtail dragonfly (Stenogomphurus rogersi) was/were spotted perched alongside a small stream located in Fairfax County, Virginia USA. All individuals featured in this photo set are male, as indicated by their indented hind wings and terminal appendages.

Male 1

The first shot is a “record shot,” that is, a quick-and-dirty shot that provides a record of the spotting. In this case, I was able to shoot one photo before Male 1 flew away. I didn’t see where he landed.

26 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Male 2

I found Male 2 perched on overhanging vegetation along a nearby cut bank in the stream channel.

26 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

Notice the prominent peach-colored schmutz on the right forewing, located near the pterostigma, that is visible in both photos of Male 2. Since I don’t see the schmutz in the photo of Male 1, I think Male 1 and 2 are probably different individuals.

26 JUN 2018 | Fairfax County, VA | Sable Clubtail (male)

New late date?

Dr. Edward Eder and I visited the same site on the same day. Dr. Eder is one of the best all-around amateur naturalists I know. Ed saw/photographed a male Sable Clubtail near the same location as my photos, a little earlier in the day. Both of us thought we’d set a new late-date for S. rogersi in Northern Virginia. As it turns out, I spotted a female Sable Clubtail on 05 July 2018. Photos of the female will be featured in my next blog post.

Copyright © 2018 Walter Sanford. All rights reserved.

Halloween Pennant (terminal appendages)

August 31, 2016

Most experienced odonate hunters would never mistake an orangish-red mature male Halloween Pennant dragonfly (Celithemis eponina) for a yellow mature female of the same species, right? Maybe, maybe not. Color is quite variable, depending upon gender, age, and natural variation. Usually it’s better to use terminal appendages to identify gender rather than color.

Female

The following Halloween Pennant was spotted at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is a female, as indicated by her terminal appendages. Female dragonflies have a pair of cerci (superior appendages) that have little or no function.

A Halloween Pennant dragonfly (Celithemis eponina) spotted at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is a female.

11 JUL 2016 | OBNWR | Halloween Pennant (female)

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

Immature male

The next Halloween Pennant dragonfly was spotted at Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is an immature male, as indicated by his yellowish coloration and terminal appendages.

A Halloween Pennant dragonfly (Celithemis eponina) spotted at Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is an immature male.

02 JUL 2016 | MRA | Halloween Pennant (immature male)

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

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”).

Female (displaying unusual coloration)

The last Halloween Pennant was spotted near the Pollinator Garden at Meadowood Recreation Area. This individual is a female, as indicated by her terminal appendages. Notice this specimen has orangish-red coloration similar to a mature male of the same species, including magenta pterostigmata.

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

  • Genus Celithemis | Celithemis eponina | Halloween Pennant | female | top view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | female | side view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | male | top view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | male | side view

Copyright © 2016 Walter Sanford. All rights reserved.

Ebony Jewelwing damselflies (male, female)

August 9, 2015

Ebony Jewelwing (Calopteryx maculata) is a member of the Family Calopterygidae (Broad-winged damselflies). They are common from May to July along wooded slow-moving streams such as Dogue Creek in Wickford Park.

Male

All male damselflies have four terminal appendages, collectively called “claspers.” Male damselfly terminal appendages don’t look exactly the same for all species of damselflies, but their function is identical.

Claspers are used to grab and hold female damselflies during mating: an upper pair of cerci (“superior appendages”) and a lower pair of paraprocts (“inferior appendages”).

An Ebony Jewelwing damselfly (Calopteryx maculata) spotted at Dogue Creek, Wickford Park, Fairfax County, Virginia USA. This individual is a male.

05 AUG 2015 | Wickford Park | Ebony Jewelwing (male)

The preceding image also shows the male hamules, …

paired structures that project from pocket under the second segment [S2] and hold female abdomen in place during copulationSource Credit: Glossary [of] Some Dragonfly Terms, by Dennis R. Paulson.

After a male damselfly grabs a female with his claspers, he transfers sperm from the genital opening under the ninth abdominal segment (S9) to his hamules, located beneath the second abdominal segment (S2). Next the pair forms the mating wheel, then the male transfers sperm from his hamules to the female through her genital pore under the eighth abdominal segment (S8).

A mating pair of Ebony Jewelwing damselflies (Calopteryx maculata) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in wheel (in heart).

06 JUN 2015 | HMP | Ebony Jewelwing (mating pair, in wheel)

The copulatory, or wheel, position is unique to the Odonata, as is the distant separation of the male’s genital opening and copulatory organs. That the position looks as much like a heart as a wheel has been noted. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 377-378). Princeton University Press. Kindle Edition.

Female A simple field marker may be used to differentiate male and female Ebony Jewelwings: females feature white pterostigmata (see below); males don’t.

An Ebony Jewelwing damselfly (Calopteryx maculata) spotted at Dogue Creek, Wickford Park, Fairfax County, Virginia USA. This individual is an adult female.

05 AUG 2015 | Wickford Park | Ebony Jewelwing (adult female)

The preceding annotated image illustrates some of the reproductive anatomy of a female Ebony Jewelwing: a cercus (pl. cerci), one of two superior appendages that have little or no function; a stylus (pl. styli), one of two structures that serve as sensors in egg positioning; and an ovipositor that is used to insert eggs into submerged vegetation (endophytic oviposition). Notice the mud on the tip of the female’s abdomen, indicating she laid eggs recently.

Copyright © 2015 Walter Sanford. All rights reserved.

Star Spangled Fourth

July 4, 2015

Happy Independence Day! The stars of this post are Spangled Skimmer dragonflies (Libellula cyanea) spotted in the fields at Huntley Meadows Park.

The Spangled Skimmer is easily differentiated from similar-looking brown-and-yellow and/or blue dragonflies by its distinctive black-and-white pterostigmas located along the leading edge of all four wings (toward the wingtips).

Females

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

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

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

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

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

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

22 MAY 2015 | Huntley Meadows Park | Spangled Skimmer (female)

Notice the following female doesn’t look as “fresh” as the females spotted during May.

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

29 JUN 2015 | Huntley Meadows Park | Spangled Skimmer (female)

Female Spangled Skimmers have a pair of flanges beneath their eighth abdominal segment (S8) that are used to scoop 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 Spangled Skimmer dragonfly (Libellula cyanea) spotted  at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

29 JUN 2015 | Huntley Meadows Park | Spangled Skimmer (female)

Males

Immature male Spangled Skimmers and immature/adult female Spangled Skimmers (shown above) are nearly identical in appearance except for their terminal appendages.

A Spangled Skimmer dragonfly (Libellula cyanea) spotted  at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

22 MAY 2015 | Huntley Meadows Park | Spangled Skimmer (immature male)

Contrast the astounding difference in appearance between immature male and adult male Spangled Skimmers.

A Spangled Skimmer dragonfly (Libellula cyanea) spotted  at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an adult male.

26 MAY 2015 | Huntley Meadows Park | Spangled Skimmer (adult male)

Related Resources:

Copyright © 2015 Walter Sanford. All rights reserved.

Bar-winged Skimmer dragonfly (mature male)

June 20, 2015

Bar-winged Skimmer dragonflies (Libellula axilena) look similar to Great Blue Skimmer dragonflies (Libellula vibrans).

A Bar-winged Skimmer dragonfly (Libellula axilena) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

10 JUN 2015 | HMP | Bar-winged Skimmer (mature male)

Several key field markers can be used to differentiate the two species of dragonflies, as shown in the following annotated images.

A Bar-winged Skimmer dragonfly (Libellula axilena) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature male.

10 JUN 2015 | HMP | Bar-winged Skimmer (mature male)

Bar-winged Skimmers have dark reddish-brown eyes and a metallic black face; Great Blue Skimmers have blue eyes and a white face. Also notice the Bar-winged Skimmer has a small black bar along the “costa” (the leading edge of both the fore- and hind wings), located between the nodus and pterostigma — hence its common name, “Bar-winged Skimmer“; the Great Blue Skimmer does not.

A Great Blue Skimmer dragonfly (Libellula vibrans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

31 MAY 2015 | HMP | Great Blue Skimmer (mature male)

Side view of Great Blue Skimmer (shown above); dorsal view (shown below).

A Great Blue Skimmer dragonfly (Libellula vibrans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young male.

31 MAY 2015 | HMP | Great Blue Skimmer (young male)

The following gallery features several more photos of the same Bar-winged Skimmer spotted at Huntley Meadows Park (HMP) on 10 June 2015.

Copyright © 2015 Walter Sanford. All rights reserved.

Widow Skimmer dragonfly (immature male)

June 16, 2015

Widow Skimmer dragonfly (Libellula luctuosa) was spotted on 06 June 2015 during a photowalk at Huntley Meadows Park (HMP). This individual is an immature male, as indicated by its coloration and terminal appendages. Immature males look similar to female Widow Skimmers.

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

As a mature male, this specimen will develop white pruinescence on its body as well as white wing spots (located between the dark wing spots and pterostigmata). The white wing spots are faintly visible in some photos, such as the one shown below.

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

I’m especially fond of head-tilts in which the dragonfly seems to display some of its personality. Sometimes I tend to project my thoughts into the mind of the dragonflies I photograph. After following this guy from perch-to-perch, I’m guessing he was thinking, “Hey pal, please stop following me!”

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

A Widow Skimmer dragonfly (Libellula luctuosa) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature male.

06 JUN 2015 | HMP | Widow Skimmer (immature male)

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

  • Genus Libellula | Libellula luctuosa | Widow Skimmer | male | top view
  • Genus Libellula | Libellula luctuosa | Widow Skimmer | male | side view
  • Genus Libellula | Libellula luctuosa | Widow Skimmer | female | top view
  • Genus Libellula | Libellula luctuosa | Widow Skimmer | female | side view

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 Widow Skimmer page. In the lower-right corner of page 2, 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.

Needham’s Skimmer dragonfly (young female)

June 8, 2015

Imagine my excitement when a flash of bright yellow flew past me as I was standing in a small meadow near a vernal pool at Huntley Meadows Park (HMP) — I thought I’d spotted the elusive Yellow-sided Skimmer dragonfly (Libellula flavida)! I say “elusive” because no one I know has ever seen a Yellow-sided Skimmer at the park, although it appears on the Friends of Huntley Meadows Park Odonata species list.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young female.

22 MAY 2015 | HMP | Needham’s Skimmer (young female)

Now imagine my disappointment when I looked closely at full-size versions of the photos I took — turns out I had seen a young female Needham’s Skimmer dragonfly (Libellula needhami), as indicated by its coloration and terminal appendages. A beautiful specimen nonetheless, but one I have seen many times at several locations.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young female.

22 MAY 2015 | HMP | Needham’s Skimmer (young female)

Notice the female’s cerci (terminal appendages) are flared in the following photo. I don’t know what the opposite of a “butt crunch” is called, but this is the pictionary definition for the word.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young female.

22 MAY 2015 | HMP | Needham’s Skimmer (young female)

The last two images in this set are used to illustrate the field markers that enabled me to identify the species for this specimen.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young female.

22 MAY 2015 | HMP | Needham’s Skimmer (young female)

Wings with veins fairly dark, [ptero]stigma and anteriormost veins yellow except basal part of costa dark before nodus. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 9291-9292). Princeton University Press. Kindle Edition.

The leading edge of a dragonfly wing is called the “costa”; the midpoint of the costa is called the “nodus.” Notice the pterostigmata are yellow and the costa is dark between the thorax and nodus, light between the nodus and wing tip — these are key field markers for Needham’s Skimmer, not Yellow-sided Skimmer.

A Needham's Skimmer dragonfly (Libellula needhami) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a young female.

22 MAY 2015 | HMP | Needham’s Skimmer (young female)

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

  • Genus Libellula | Libellula needhami | Needham’s Skimmer | female | top view
  • Genus Libellula | Libellula needhami | Needham’s Skimmer | female | side view
  • Genus Libellula | Libellula flavida | Yellow-sided Skimmer | female | top view
  • Genus Libellula | Libellula flavida | Yellow-sided Skimmer | female | side view

Copyright © 2015 Walter Sanford. All rights reserved.

Eat or be eaten

November 2, 2014

Consider the simple life of a female Autumn Meadowhawk dragonfly (Sympetrum vicinum): One day she’s basking in warm afternoon sunlight, eating a smaller winged insect while waiting to mate with a passing male. Life is good.

Autumn Meadowhawk dragonfly (female, eating unknown prey)

20 October 2014 | Huntley Meadows Park

A few days later, the tables were turned and the female Autumn Meadowhawk was eaten by a larger male Shadow Darner dragonfly (Aeshna umbrosa), as shown in the following time-series of photos.

Shadow Darner dragonfly (male, eating an Autumn Meadowhawk dragonfly)

24 October 2014 | Huntley Meadows Park

The Shadow Darner’s prey is a female Autumn Meadowhawk, as indicated by several field markers including its coloration and red pterostigmata; also, the abdomen of female Autumn Meadowhawks is thicker near the thorax than for males.

Although it is improbable the two female Autumn Meadowhawk dragonflies shown in these photographs are the same individual, they were spotted near the same vernal pool in the forest at Huntley Meadows Park.

Shadow Darner dragonfly (male, eating an Autumn Meadowhawk dragonfly)

24 October 2014 | Huntley Meadows Park

The Shadow Darner ate the Autumn Meadowhawk quickly. Game over, man!

Shadow Darner dragonfly (male)

24 October 2014 | Huntley Meadows Park

The Backstory: In a recent post in the Northeast Odonata Facebook group I said, “The [Shadow Darner] dragonfly flew several laps around a meadow near a vernal pool, perching in three places for no more than a second each time.” Since then, I have observed Shadow Darners at the same location several times. They fly close to the ground most of the time, dipping in-and-out of the ground cover repeatedly. Initially, I thought they were looking for a place to rest; now I think they are searching for food. [Some odonate experts speculate male Shadow Darners behave like this when they are looking for a female.]

On Friday, 24 October 2014, I saw a Shadow Darner dip toward the grass: it emerged with a relatively large insect in its grasp; after a lap or two above the field, the Shadow Darner landed on a nearby tree. Turns out the darner had captured a female Autumn Meadowhawk dragonfly!

Has anyone observed Shadow Darners hawking like the ones at Huntley Meadows Park?

Copyright © 2014 Walter Sanford. All rights reserved.

Spangled Skimmers: immature male versus female

July 7, 2014

Spangled Skimmer dragonflies (Libellula cyanea) are easy to recognize because of their distinctive black-and-white pterostigmata, located on the leading edge of all four wings, toward the wing tips. Spangled Skimmers display sexual dimorphism, that is, coloration is different for mature males and females.

Immature male- and mature female Spangled Skimmers are nearly identical in appearance except for their terminal appendages. Another useful field marker: females have broad dark wing tips; males, not so much.

The following gallery features an immature male spotted on 25 May 2014 near a vernal pool far from the central wetland area at Huntley Meadows Park.

The next gallery shows a female spotted on 06 June 2014 along the gravel road between the Hike-Bike Trail and the new observation platform located on the southwestern side of the central wetland area.

Notice the dark spots on the female’s wing tips. A side view of the female (see Photo 6) shows another observable difference between male- and female Spangled Skimmers: Females have a pair of flanges beneath their eighth abdominal segment (segments are numbered from front to back) that are used to scoop and hold a few drops of water during oviposition, hence the family name “Skimmer.” Photo 3 (above) shows a partial side view of the immature male. Look underneath his eighth abdominal segment … no flanges!

The following slideshow features the two photos in this post that show the difference between the terminal appendages of male- and female Spangled Skimmer dragonflies most clearly. 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”). Female dragonflies have a pair of cerci (superior appendages) that have little or no function. Can you see the difference between their terminal appendages?

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Copyright © 2014 Walter Sanford. All rights reserved.


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