Spangled Skimmer dragonfly terminal appendages

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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3 Responses to “Spangled Skimmer dragonfly terminal appendages”

  1. Mike Powell Says:

    Great explanation and illustration of the terminal appendages. Your annotations and super sharp images made it really easy to see and understand the differences.

  2. Spangled Skimmer dragonfly (teneral male) | walter sanford's photoblog Says:

    […] 20 MAY 2016 | ABWR | Spangled Skimmer (teneral male) […]

  3. Star Spangled Fourth (2016 Edition) | walter sanford's photoblog Says:

    […] In celebration of the Fourth of July, it is my honor to present a color guard of several Spangled Skimmer dragonflies (Libellula cyanea) spotted at three locations in Northern Virginia. All three individuals are males, as indicated by their coloration and terminal appendages. […]

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