Dragonfly Claspers & Genitalia
In-hand examination of the genitalia and abdominal appendages is necessary for identification
of some of the hard to identify species, as kinky as it might sound! To do this
takes some practice, patience, a magnifying lens, and some basics of dragonfly anatomy.
Many field guides incorporate illustrations of appendages to make this easier.
Dragonflies of North America, by Westfall and May, has scans of most species.
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Dorsal and lateral view of the abdominal claspers of a Shadow Darner, Aeshna umbrosa
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The tip of the male abdomen has appendages, often called claspers, that are diagnostic
for most species, especially the Darners, Clubtails and Emeralds. Females
have terminal appendages but these are rarely of use in ID except in a few cases
where their length may be significant.
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PICTURE
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PICTURE
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Scans of secondary genitalia of a Whiffling Meandowhawk and a Sniffling Meadowhawk |
In a number of species, especially among the Skimmer family, these terminal appendages
don't vary much between the species. In some of these, the secondary genitalia under
abdominal segments 1&2 may be of some help. But learning to see them with
a hand lens can take a bit of practice and even then some species are frustratingly
similar or show variation within the species.
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Ovipositor of a Fine-lined Emerald with eggs
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Female dragonflies: Some females canbe identified by the shape of the sub-genital
plate or ovipositor under abdominal segments 8&9.
To learn more about the names and function of these body parts, you can visit our
biology pages.
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