Sometime during the late 1950s or early 1960s, my father bought a new car. That was a big deal in our family. My family was poor, although I didn’t realize it when I was a young boy. We couldn’t afford a new car very often. I don’t remember many details about the car other than it was a sky blue Plymouth with tail fins. Big tail fins! My best guess is the car was a four-door Plymouth Fury, sold from 1957 – 1960.
Some odonate exuviae/larvae remind me of the tail fins on my father’s Plymouth automobile. Go figure. Anyway, pattern recognition can be used to make it a little easier to identify exuviae. For example, when I see an exuvia with long “tail fins,” my first thought is it’s probably from one of two genera, possibly three: genus Pantala; genus Tramea; or maybe genus Celithemis.
Dichotomous keys
The following couplet from Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz, can be used to differentiate exuvia from Genus Pantala and Genus Tramea.
p. 37, Key to the Genera of the Family Libellulidae
12a – Superior abdominal appendage (epiproct) as long as, or longer than inferiors [paraprocts]. Pantala
12b – Superior abdominal appendage (epiproct) shorter than inferiors [paraprocts]. Tramea
Soltesz, p. 39.
Soltesz, p. 40.
Soltesz, p. 41.
Genus Pantala (Rainpool Gliders)
The genus Pantala includes two (2) species in North America: Spot-winged Glider (Pantala hymenaea); and Wandering Glider (Pantala flavescens).
Spot-winged Glider and Wandering Glider larvae/exuviae look similar. The lateral spines on abdominal segment nine (S9) are noticeably shorter for P. hymenaea (shown left) than P. flavescens (shown right) — a key field mark that can be used to differentiate the two species.
Genus Tramea (Saddlebags)
The genus Tramea includes seven (7) species in North America. Two of those species are found commonly in the Commonwealth of Virginia: Black Saddlebags (Tramea lacerata); and Carolina Saddlebags (Tramea carolina).
Carolina Saddlebags
A Carolina Saddlebags dragonfly (Tramea carolina) larva was collected by Andy Davidson near Richmond, Virginia USA, and reared to maturity. Andy saved the exuvia after emergence.
A vertical white line marks the mid-dorsal length of abdominal segment nine (S9), as shown in the following annotated image; the vertical black line labeled “mid-dorsal length” is the same length as the white line. Notice the lateral spines of abdominal segment nine (S9) are much longer than its mid-dorsal length.
Carolina Saddlebags (Tramea carolina) | exuvia (anal pyramid)
(See a full-size version of the original photo, without annotation.)
One of the keys to identifying skimmer dragonflies to the species level is to carefully examine the anal pyramid (S10), including the cerci (sing. cercus), epiproct, and paraprocts. Notice the epiproct is shorter than the paraprocts.
There is a lot of “seaweed” (aquatic vegetation) clinging to the exuvia, especially noticeable at the posterior end. Some collectors like to clean their specimens; I prefer to photograph them “as is.”
Black Saddlebags
Athough adult Black Saddlebags dragonflies (Tramea lacerata) are relatively common in Virginia, the author has never seen an exuvia from this species.
Genus Celithemis (Pennants)
The genus Celithemis includes eight (8) species in North America. The author has a specimen from only one of these species in his collection.
A Calico Pennant dragonfly (Celithemis elisa) evuvia was collected by Sue and John Gregoire at Kestrel Haven Migration Observatory. For more than a decade, Sue and John have closely monitored the annual emergence of a large population of C. elisa at their farm pond.
Notice the long lateral spines that look similar to larvae/exuviae in genus Pantala and genus Tramea.
Related Resources
Identification Keys to Northeastern Anisoptera Larvae, compiled by Ken Soltesz.
- p. 36 = Key to the Genera of Family Libellulidae
- p. 37 = Pantala, Tramea
- p. 39 = Key to the species of genus Pantala: hymenaea; flavescens
- p. 41 = Key to the species of genus Tramea: carolina; lacerta
A Checklist of North American Odonata – Including English Name, Etymology, Type Locality, and Distribution, by Dennis R. Paulson and Sidney W. Dunkle.
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