Posts Tagged ‘nodus’

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 marks 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.

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 marks 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 marks 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.

Needham’s Skimmer dragonfly (male)

June 30, 2012

A Needham’s Skimmer dragonfly (Libellula needhami) was spotted along the boardwalk that goes through the central wetland area at Huntley Meadows Park. This individual is a male, as indicated by its reddish-orange coloration and the terminal appendages at the end of its abdomen.

Needham’s Skimmer dragonflies and Golden-winged Skimmer dragonflies (Libellula auripennis) are similar in appearance. Refer to the following gallery of graphics for aid in identifying the two species.

Row 1: Diagnosis of Libellula needhami; Diagnosis of Libellula auripennis.
Row 2: Diagnostic features of several specimens of Libellula needhami (Needham’s Skimmer); Diagnostic features of several specimens of Libellula auripennis (Golden-winged Skimmer).
Source Credit: Graphics used with written permission from Gayle and Jeanell Strickland.

Post Update

Look at the front wings for all species of dragonflies. The leading edge of each wing is called the “costa.” Halfway along the costa is a “dividing line” called the “nodus.”

Gomphidae wing structure. Source Credit: Insect wing (Wikipedia).

For Needham’s Skimmer (L. needhami), notice the costa is dark from the nodus to the body, and yellow-orange from the nodus to the wing tips; for Golden-winged Skimmer (L. auripennis), the entire length of the costa is yellow-orange. This is perhaps the best field mark to differentiate the two species.

Copyright © 2012-2020 Walter Sanford. All rights reserved. www.wsanford.com


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