Archive for June, 2015

Spangled Skimmer dragonfly terminal appendages

June 10, 2015

Spangled Skimmer (Libellula cyanea) 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).

Spangled Skimmers display sexual dimorphism. Although mature males and females look different, immature males and females look similar. Terminal appendages may be used to differentiate immature males from females.

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 | HMP | Spangled Skimmer (female)

Look closely at the full-size version of the following annotated image. Female Spangled Skimmers have two 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.

Another useful field marker that may be used to differentiate males from females: females have broad dark wing tips; males, not so much.

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”).

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

22 MAY 2015 | HMP | Spangled Skimmer (immature male)

Blue pruinescence that covers the body of following mature male Spangled Skimmer makes it look quite different from the immature male (shown above), other than its terminal appendages and distinctive black-and-white pterostigmata.

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

26 JUN 2012 | HMP | Spangled Skimmer (mature male)

Related Resources: Odonate Terminal Appendages.

Copyright © 2015 Walter Sanford. All rights reserved.

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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.

Painted Skimmer dragonfly (female, laying eggs)

June 6, 2015

Painted Skimmer (Libellula semifasciata) is a member of the Skimmer Family of dragonflies. Females lay eggs (oviposition) by skimming the water surface repeatedly, hence the family name “Skimmer“; two flanges beneath their eighth abdominal segment (S8) scoop water that is used to flick fertilized eggs toward the shore, as illustrated in the following annotated image. Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

The following movie shows a female Painted Skimmer dragonfly laying eggs in a vernal pool at Huntley Meadows Park on 20 May 2015. (Same day, different time. Same park, different location. Same species, different female.)

Editor’s Note: Copulation between male and female Painted Skimmers occurs in-flight and is very brief, lasting just a few seconds. In my experience, oviposition is brief too. My camera was set up for shooting still photographs when I spotted the mating pair; by the time I moved into position, the pair had separated and the female was laying eggs. Fortunately I had the presence of mind to shoot video rather than stills. The video quality isn’t great, buy hey, at least I captured the moment, albeit brief!

Copyright © 2015 Walter Sanford. All rights reserved.

Painted Skimmer dragonfly (female)

June 4, 2015

The following gallery features still photos of the same female Painted Skimmer dragonfly (Libellula semifasciata) who starred in the movie, “Painted Skimmer dragonfly (female, breathing and grooming).”

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

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

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

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

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

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

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

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

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

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

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

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

The following photo is the last one I shot (by hand-holding the camera) before setting up my tripod to shoot some video clips.

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

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

Copyright © 2015 Walter Sanford. All rights reserved.

Painted Skimmer dragonfly (female, breathing and grooming)

June 2, 2015

The following movie features a Painted Skimmer dragonfly (Libellula semifasciata) spotted on 20 May 2015 during a photowalk alongside the wetlands at Huntley Meadows Park. This individual is a female, as indicated by its terminal appendages.

Dragonflies breathe through small holes in the underside of their thorax and abdomen called “spiracles.” Notice the dragonfly’s thorax and abdomen expanding and contracting as she inhales and exhales.

The female appears to be grooming while perching on vegetation, using her front legs to wipe her eyes and face. The author has observed many species of dragonflies engaged in similar behavior.

Tech Tips: The preceding movie looks better viewed in full-screen mode.

The video clips used to create this movie were shot on a very windy day. I used a tripod for my camera and centered the subject in each clip, but the wind caused the dragonfly to drift off-center at times. Not that I’m a perfectionist or anything.

Related Rescources:

Copyright © 2015 Walter Sanford. All rights reserved.


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