06 OCT 2014 | HMP | Slender Spreadwing damselfly (female)
The preceding photograph shows a Slender Spreadwing damselfly (Lestes rectangularis) spotted near a vernal pool at Huntley Meadows Park (HMP). This individual is a female as indicated by its terminal appendages and the ovipositor located on the underside of the posterior abdomen.
Copyright © 2015 Walter Sanford. All rights reserved.
The following Great Spreadwing damselfly (Archilestes grandis) was spotted on 20 October 2014 near a vernal pool in the forest at Huntley Meadows Park. This individual is a male, as indicated by its coloration, hamules, and terminal appendages.
With handsome azurite-colored eyes complemented by green and yellow racing stripes on their thorax, male Great Spreadwings are one of my favorite damselflies!
Copyright © 2015 Walter Sanford. All rights reserved.
The following annotated photograph illustrates some of the external reproductive anatomy of an adult female Swamp Darner dragonfly (Epiaeschna heros), shown laying eggs (ovipostion) in mud: a pair of cerci (superior appendages) that have little or no function; a stylus (pl. styli), one of two structures that serve as sensors in egg positioning; and an ovipositor that is used to insert eggs into wet dead wood, mud, etc.
The preceding photograph was taken on 02 June 2014 in a drainage ditch located near a vernal pool at Huntley Meadows Park. The photograph was voted one of my Top 10 Photos of 2014 in the first annual Peopoll’s Choice Awards.
Editor’s Note: Thanks to Benjamin A. Coulter, member of the Northeast Odonata Facegroup, for kindly identifying the stylus (pl. styli) located between the cerci and ovipositor.
Related Resources: Digital Dragonflies, presenting high-resolution digital scans of living dragonflies.
Copyright © 2015 Walter Sanford. All rights reserved.
As I was photographing a female Autumn Meadowhawk dragonfly (Sympetrum vicinum) perching on the boardwalk at Huntley Meadows Park on 11 November 2014, I noticed a small spider moving toward the dragonfly quickly.
I remember thinking, “No way this smaller spider is preying upon a larger dragonfly.” Turns out the spider actually may have been stalking the dragonfly!
Apparently there is some risk associated with a dragonfly attempting to capture a jumping spider. Fitch (1963) observed an adult Phidippus audax (Hentz) jumping several inches into the air in unsuccessful attempts to capture adult dragonflies overhead and on other occasions observed P. audax carrying dragonflies. Edwards (1980) presents two additional records of P. audax and P. otiosus (Hentz) capturing adult Libellulidae. Source Credit: DRAGONFLY PREDATION UPON PHIDIPPUS AUDAX (ARANEAE, SALTICIDE). 1988. The Journal of Arachnology 16:121.
Thanks to the experts on BugGuide Facebook group for identifying the spider as a type of jumping spider, probably a male Phidippus sp. The screw hole in the boardwalk — an estimated 1/4″ in diameter — provides a sense of scale.
You can see the swollen pedipalps on either side of the “fangs.” That’s where the male spider carries his sperm. Also a female would have a larger abdomen to produce the eggs. Source Credit: Dennis Haines, BugGuide Facebook group.
The green areas are the fangs Dennis mentioned. Source Credit: Sandy Simpson, BugGuide Facebook group.
In case you’re wondering how the close encounter turned out, let’s just say the dragonfly’s spider sense was tingling and she opted for flight rather than fight. Score one for Team Dragonflies!
I’m looking forward to using my new Raynox DCR-250 close-up filter to shoot some macro photographs of this type of spider.
Copyright © 2015 Walter Sanford. All rights reserved.
Some species of dragonflies display sexual dimorphism; females are polymorphic for a smaller subset of those species. Andromorph females are male-like in color; heteromorph females are duller in color than males.
Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) display sexual dimorphism, and female Blue-faced Meadowhawks are polymorphic.
The following time-series of photos shows a mating pair of Blue-faced Meadowhawk dragonflies, spotted on 20 October 2014 near a vernal pool in the forest at Huntley Meadows Park. The pair is “in wheel”: the male is on top; the female is on the bottom.
The last photo in the set shows some of the female’s red coloration, indicating she’s an andromorph. Look closely at the dorsum of the female’s abdomen, as shown in a full-size version of the photograph.
Copyright © 2015 Walter Sanford. All rights reserved.
It may seem like all dragonflies look alike when you’re beginning to learn how to identify dragonflies. For example, all dragonflies have large, multifaceted compound eyes. Look closely. Careful observation of the color, shape, and size of eyes should enable you to quickly identify the family (or families) of dragonflies to which a specimen may belong.
The following field markers — used in combination with a good field guide to dragonflies, a species list for your location, and the process of elimination — should enable you to identify unknown specimens more quickly than randomly trying to find a match between your specimen and one of the 316 of species of dragonflies known to occur in the United States!
Clubtail Family (and Petaltail Family)
The eyes of clubtail dragonflies (and petaltails) are widely separated, somewhat similar to the eyes of damselflies. The Clubtail Family is the second largest family of dragonflies, so this field marker should be useful for identifying a lot of dragonflies to the family level — if only clubtails were as easy to identify down to the species level!
09 MAY 2013 | Meadowood Recreation Area | Ashy/Lancet Clubtail (female)
The preceding dragonfly is either an Ashy Clubtail (Gomphus lividus) or Lancet Clubtail (Gomphis exilis). Ashy- and Lancet Clubtail dragonflies are similar in appearance and difficult to differentiate with complete certainty. But one look at those eyes and you know it’s definitely some species of clubtail!
Spiketail Family
Notice the eyes of the following dragonfly nearly touch at a point between its eyes — that’s a distinctive field marker for the Spiketail Family.
09 MAY 2013 | Meadowood Recreation Area | Brown Spiketail (female)
Cruiser, Emerald, and Skimmer Families
In a few families of dragonflies, the eyes meet along a short seam near the face.
The Skimmer Family is the largest family of dragonflies. Many species of Skimmers are common and fairly easy to identify.
There are fewer species of dragonflies in the Cruiser Family than the Skimmer Family; no other dragonflies in the United States look similar to cruisers.
02 MAY 2013 | Accotink Bay Wildlife Refuge | Stream Cruiser (male)
Many species of the Emerald Family feature distinctive bright green eyes, hence the family name.
25 JUL 2012 | The Wildlife Sanctuary | Mocha Emerald (male)
Darner Family
The eyes of Darners meet along a long seam from front-to-back.
14 AUG 2012 | Huntley Meadows Park | Common Green Darner (mating pair)
Self-test
OK, let’s apply what you just learned. Looking at the eyes only, can you identify the family for the following dragonfly? If you would like to know whether your answer is correct, then please leave a comment.
Teacher’s Note: In order to avoid revealing the answer to the one-question quiz as soon as the first person comments, I changed the settings for this blog so that comments must be approved manually.
26 JUN 2015 | Wickford Park | [Insert family name here.]
Copyright © 2015 Walter Sanford. All rights reserved.
The theme of the “sampler series” is simple. Male dragonfly claspers come in a variety of shapes and sizes, but their function is identical for all species of dragonflies: male dragonflies use their claspers to grab and hold female dragonflies during mating.
There are seven families of dragonflies. Part 2 (of 2) features a sampler of select images showing male dragonfly claspers from the Emerald Family, Skimmer Family, and Spiketail Family. The author never has been fortunate to photograph either species of the Petaltail Family.
Emerald Family
The following image shows a Slender Baskettail dragonfly (Epitheca costalis) spotted in an open field along the trail to Hidden Pond, a small lake located at Meadowood Recreation Area.
01 MAY 2013 | Meadowood Recreation Area | Slender Baskettail (male)
Skimmer Family
The next image shows a Bar-winged Skimmer dragonfly (Libellula axilena) spotted near a vernal pool in the forest at Huntley Meadows Park. Many members of the Skimmer Family have terminal appendages that look similar to the Bar-winged Skimmer, such as Painted Skimmer, Eastern Pondhawk, and Blue-faced Meadowhawk, to name a few species.
31 MAY 2014 | Huntley Meadows Park | Bar-winged Skimmer (male)
The following image shows a battle-scarred Black Saddlebags dragonfly (Tramea lacerata) spotted alongside the boardwalk in the central wetland area hemi-marsh at Huntley Meadows Park. Black Saddlebags’ terminal appendages are unlike most members of the Skimmer Family.
12 SEP 2014 | Huntley Meadows Park | Black Saddlebags (male)
Spiketail Family
The last image shows an Arrowhead Spiketail dragonfly (Cordulegaster obliqua) I discovered while exploring a small stream at a remote location in Huntley Meadows Park.
07 JUL 2014 | Huntley Meadows Park | Arrowhead Spiketail (male)
Related Resources:
Editor’s Notes: Part 1 (of 2) features a sampler of select images showing male dragonfly dragonfly claspers from the Clubtail Family, Cruiser Family, and Darner Family. The author has never been fortunate to photograph either species of the Petaltail Family.
Copyright © 2015 Walter Sanford. All rights reserved.
All 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”). Claspers come in a variety of shapes and sizes, but their function is identical for all species of dragonflies.
There are seven families of dragonflies. Part 1 (of 2) features a sampler of select images showing male dragonfly claspers from the Clubtail Family, Cruiser Family, and Darner Family.
Clubtail Family
The following image shows a male Ashy Clubtail dragonfly (Gomphus lividus) perching on the ground in a field located near Giles Run at Meadowood Recreation Area in Fairfax County, Virginia.
02 MAY 2014 | Meadowood Recreation Area | Ashy Clubtail (male)
Cruiser Family
The next image shows a male Stream Cruiser dragonfly (Didymops transversa) spotted along “Beaver Pond Loop Trail” at Accotink Bay Wildlife Refuge, a 1,200 acre preserve located at Army Garrison Fort Belvoir, Fairfax County, Virginia.
02 May 2013 | Accotink Bay Wildlife Refuge | Stream Cruiser (male)
Darner Family
The last image shows a male Shadow Darner dragonfly (Aeshna umbrosa) spotted near a vernal pool in the forest at Huntley Meadows Park.
24 OCT2014 | Huntley Meadows Park | Shadow Darner (male)
Related Resources:
Editor’s Notes: Part 2 (of 2) will feature a sampler of select images showing male dragonfly dragonfly claspers from the Emerald Family, Skimmer Family, and Spiketail Family. The author never has been fortunate to photograph either species of the Petaltail Family.
Copyright © 2015 Walter Sanford. All rights reserved.
Some species of dragonflies display sexual dimorphism; females are polymorphic for a smaller subset of those species. Andromorph females are male-like in color; heteromorph females are duller in color than males.
Terminal appendages are important field marks that can be used to differentiate adult males and adult andromorph females of the same species.
08 OCT 2013 | Huntley Meadows Park | Blue-faced Meadowhawk (male)
Andromorph female Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum), like the one shown below, are less common than heteromorph females. Andromorphs have a red abdomen with black rings, like male Blue-faced Meadowhawks; unlike males, most female faces are tan and their terminal appendages look different than male appendages.
08 OCT 2013 | Huntley Meadows Park | Blue-faced Meadowhawk (female)
The following photo shows a heteromorph female Blue-faced Meadowhawk dragonfly. Heteromorphs have a tan abdomen with black rings.
27 SEP 2013 | Huntley Meadows Park | Blue-faced Meadowhawk (female)
Editor’s Note: Some odonate experts favor the term “polychromatism” rather than “polymorphism.”
Polychromatism has often (inappropriately) been termed polymorphism. I follow the terminology recommended by Don Hilton (1987), in which the female coloration is termed gynochromatypic and that of the male androchromatypic. Source Credit: Corbet, Phillip S (2004). Dragonflies: Behaviour and Ecology of Odonata. [The 1962 edition of the book is available online: A Biology of Dragonflies.]
Related Resources:
Copyright © 2015 Walter Sanford. All rights reserved.
“…as indicated by its terminal appendages” is a stock phrase used in many, if not most, of my dragonfly-related posts. This post will answer two questions:
Let’s begin by answering the first question.
Male terminal appendages
All 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”). Male dragonfly terminal appendages don’t look exactly the same for all species of dragonflies, but their function is identical.
06 JUN 2014 | Huntley Meadows Park | Painted Skimmer (male)
Can you identify the male’s three terminal appendages in the following photo? If necessary, then refer to the annotated image (shown above).
23 MAY 2014 | Huntley Meadows Park | Painted Skimmer (male)
Female terminal appendages
Female dragonflies have a pair of cerci (superior appendages) that have little or no function.
23 MAY 2014 | Huntley Meadows Park | Painted Skimmer (female)
Can you identify the female’s two terminal appendages in the following photo? If necessary, then refer to the annotated image (shown above).
23 MAY 2014 | Huntley Meadows Park | Painted Skimmer (female)
Composite image
Notice the differences between female- and male terminal appendages, as shown in the following composite image: female appendages are shown in the background photo; male appendages are shown in the inset photo. See a full-size version of the composite image for a clearer view of the side-by-side comparison of female/male terminal appendages. The difference is obvious, isn’t it?
Composite image contrasting female/male terminal appendages.
Why are terminal appendages important field markers in dragonfly identification?
When you’re ready to move to the next level of dragonfly spotting (see “Step 2” of 5), from say the beginner level to the intermediate/advanced intermediate level, you must learn to identify terminal appendages in order to differentiate males and females of the same species.
It all comes down to sexual dimorphism: mature males and mature females are either identical/nearly identical in appearance; or mature males and mature females are different in appearance, especially their coloration.
Related Resources:
Copyright © 2015 Walter Sanford. All rights reserved.
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