A Southern Fortnight, Part 6 – Damselfly reproductive anatomy

The Backstory: A Southern Fortnight

For the first two weeks during May 2015, Southern Spreadwing damselflies (Lestes australis) were observed at a vernal pool and nearby drainage ditch in the forest at Huntley Meadows Park. I spotted approximately six males and several females during the fortnight. Their sudden disappearance seemed to coincide with a population explosion of Eastern Pondhawk dragonflies (Erythemis simplicicollis) in mid-May. Eastern Pondhawks, especially females, are voracious predators with a penchant for preying upon damselflies.


The following annotated image illustrates some of the reproductive anatomy of male and female Southern Spreadwing damselflies.

A mating pair of Southern Spreadwing damselflies (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem; the female is laying eggs (oviposition).

08 MAY 2015 | HMP | Southern Spreadwing (mating pair, in tandem)

The following annotated image illustrates some of the reproductive anatomy of a female Southern Spreadwing: two cerci (sing. cercus), superior appendages that have little or no function; two styli (sing. stylus), structures that serve as sensors in egg positioning; and an ovipositor  (shown above) that is used to insert eggs into vegetation (endophytic oviposition).

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This is the female member of a mating pair, resting after laying eggs (oviposition).

07 MAY 2015 | HMP | Southern Spreadwing (adult female)

According to Ed Lam, author and illustrator of Damselflies of the Northeast, “male Southern and Sweetflag cannot be separated in the field.” It is possible to reverse-engineer a positive identification based upon a single key field marker for female specimens of the two species: Southern Spreadwing females have a much smaller ovipositor than Sweetflag Spreadwing females, as illustrated in the following references.

Sidebar: Damselfly Hook-up and Copulation

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, shown above, 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). The beginning-to-end process is shown in the following still photos and two-part series of videos.

Digital Scans:

Copyright © 2015 Walter Sanford. All rights reserved.

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2 Responses to “A Southern Fortnight, Part 6 – Damselfly reproductive anatomy”

  1. Voltinism | walter sanford's photoblog Says:

    […] 10 OCT 2016 | Huntley Meadows Park | Southern Spreadwing (female) […]

  2. Southern Spreadwing at MNWP | walter sanford's photoblog Says:

    […] The first individual is a female, as indicated by her coloration and terminal appendages. […]

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