Posts Tagged ‘flanges’

Summertime is skimmer time

July 31, 2017

Refer to the Dragonflies of Northern Virginia Calendar of Flight Periods by Kevin Munroe, former manager at Huntley Meadows Park. Notice the flight period for most Skimmers (Family Libellulidae) is centered on June, July, and August. Since meteorological summer is defined as June, July, and August, summertime is skimmer time.

A female Slaty Skimmer dragonfly (Libellula incesta) was spotted during a photowalk at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA, as indicated by her mostly black femora, brown face, and terminal appendages.

Female Slaty 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.”

Female Slaty Skimmer dragonflies and female Great Blue Skimmer dragonflies (Libellula vibrans) look similar. The following blog post provides guidance regarding key field markers that can be used to differentiate the two species: Great Blue Skimmer dragonfly (young female).

Copyright © 2017 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.

Slaty Skimmer dragonfly (female, laying eggs)

June 28, 2015

Slaty Skimmer (Libellula incesta) 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 shore, as illustrated in the following annotated image. Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.

A Slaty Skimmer dragonfly (Libellula incesta) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a mature female member of a mating pair.

10 JUN 2015 | Huntley Meadows Park | Slaty Skimmer (mature female)

The preceding still photo shows a mature female Slaty Skimmer dragonfly resting immediately after copulation.

The following movie shows the same female laying eggs in a large pool of water downstream from the central wetland area at Huntley Meadows Park on 10 June 2015.

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

Copyright © 2015 Walter Sanford. All rights reserved.

Great Blue Skimmer dragonfly (young female)

June 12, 2015

A Great Blue Skimmer dragonfly (Libellula vibrans) was spotted on 20 May 2015 during a photowalk alongside the wetlands at Huntley Meadows Park (HMP). This individual is a young female, as indicated by its coloration and terminal appendages.

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

20 MAY 2015 | HMP | Great Blue Skimmer (young female)

The young female was sheltering in vegetation close to the ground.

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

20 MAY 2015 | HMP | Great Blue Skimmer (young female)

She was quite skittish, flying to a new location whenever I violated her comfort zone.

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

20 MAY 2015 | HMP | Great Blue Skimmer (young female)

Look closely at the full-size version of the following annotated image. Female Great Blue 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 Great Blue Skimmer dragonfly (Libellula vibrans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is an immature female.

20 MAY 2015 | HMP | Great Blue Skimmer (young female)

Immature Great Blue Skimmer dragonflies and immature Slaty Skimmer dragonflies (Libellula incesta) — including both females and males — look very similar. In my opinion, the best field marker for differentiating the two species is femur coloration: Great Blue Skimmer femora are mostly tan; Slaty Skimmer femora are mostly black.

The following female Slaty Skimmer was spotted along the “Hike-Bike Trail” at Huntley Meadows Park. Contrast the difference in coloration of the Slaty Skimmer femurs (below) with the Great Blue Skimmer femurs (above).

A Slaty Skimmer dragonfly (Libellula incesta) spotted along the "Hike-Bike Trail" at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female.

04 JUN 2012 | HMP | Slaty Skimmer (young female)

Related Resources:

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

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

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

Digital scans by G & J Strickland:

Copyright © 2015 Walter Sanford. All rights reserved.

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.

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.


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