Archive for May, 2013

Blue Corporal dragonfly (mature female)

May 30, 2013

The following photos show a Blue Corporal dragonfly (Ladona deplanata) spotted at Meadowood Recreation Area, Fairfax County, Virginia USA. This individual is a mature female as indicated by its coloration and terminal appendages. Contrast the appearance of a mature female Blue Corporal versus immature females of the same species.

Blue Corporal dragonfly (mature female) Blue Corporal dragonfly (mature female)

Next post: Blue Corporal dragonflies (immature males).

Copyright © 2013 Walter Sanford. All rights reserved.

Blue Corporal dragonflies (immature females)

May 28, 2013

The following gallery shows several Blue Corporal dragonflies (Ladona deplanata) spotted on the earthen dam at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. These individuals are immature females as indicated by their coloration and terminal appendages.

Next post: Blue Corporal dragonfly (mature female).

Copyright © 2013 Walter Sanford. All rights reserved.

Brown Spiketail dragonfly (female)

May 26, 2013

The following photo gallery shows a female Brown Spiketail dragonfly (Cordulegaster bilineata) perching near the ground in an open field along the trail to Hidden Pond, a small lake located at Meadowood Recreation Area in Fairfax County, Virginia USA.

Why are Spiketail dragonflies called “spiketails,” and how do I know this individual is a female? The answer to both questions is illustrated in the following annotated close-up photograph of the posterior end of the Brown Spiketail dragonfly’s abdomen.

Brown-Spiketail_f_anatomy

All female dragonflies have a pair of cerci (superior appendages) that have little or no function. Notice the spike-shaped subgenital plate.

Spiketail dragonflies are so named because the female’s long [subgenital plate], or egg-laying organ, extends beyond the tip of the abdomen. Source Credit: New York State Department of Environmental Conservation.

Thanks to Richard Orr, renowned expert on dragonflies and damselflies of the mid-Atlantic region, for verifying my tentative indentification of both the gender of the dragonfly and some of its anatomical parts.

Related Resources: Odonate Terminal Appendages.

Copyright © 2013 Walter Sanford. All rights reserved.

Ashy- or Lancet Clubtail dragonfly (redux)

May 24, 2013

The following photographs show a Clubtail dragonfly perching on the ground along the earthen dam at Hidden Pond, a small lake located at Meadowood Recreation Area in Fairfax County, Virginia USA. This individual 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. Anyone care to offer an expert opinion?

Ashy- or Lancet Clubtail dragonfly Ashy- or Lancet Clubtail dragonfly

Editor’s Note: According to Ed Lam, author and illustrator of Damselflies of the Northeast, this individual is definitely female but the species is indefinite.

In the pictures where the abdomen tip is obscured, the rounded shape of the base of the hind wing identifies it as a female. Not going to guess on the … [species]. That’s the way it goes sometimes.

Thanks for your help, Ed!

Copyright © 2013 Walter Sanford. All rights reserved.

Zebra Swallowtail butterfly

May 22, 2013

The following photograph shows a Zebra Swallowtail butterfly (Protographium marcellus) 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 USA.

Zebra Swallowtail butterfly

Pawpaw, relatively common at Accotink Bay Wildlife Preserve, is the host plant for Protographium marcellus.

Caterpillar Hosts: Shrubs of the genus Asimina (pawpaw) in the Annonaceae family. Young plants are preferred.” Source Credit: Butterflies and Moths of North America.

Copyright © 2013 Walter Sanford. All rights reserved.

Slender Baskettail dragonfly (male)

May 20, 2013

The following photograph shows a Slender Baskettail dragonfly (Epitheca costalis) perching a few feet above the ground. This individual is a male as indicated by the terminal appendages at the end of its abdomen. Thanks to Dr. John Abbott, Odonata Central, for verifying my tentative identification.

Slender Baskettail dragonfly (male)

This specimen was spotted in an open field along the trail to Hidden Pond, a small lake located at Meadowood Recreation Area in Fairfax County, Virginia USA.

Copyright © 2013 Walter Sanford. All rights reserved.

Common Baskettail dragonflies (females)

May 18, 2013

The following photo gallery shows a couple of dragonflies spotted in an open field along the trail to Hidden Pond, a small lake located at Meadowood Recreation Area in Fairfax County, Virginia USA. These specimens are probably Common Baskettail dragonflies (Epitheca cynosura) based upon the width-to-length ratios of their abdominal segments, according to Dr. John Abbott at Odonata Central.

I think these individuals are females, as indicated by their terminal appendages. Can I get an expert second opinion?

Editor’s Note: According to Ed Lam, author and illustrator of Damselflies of the Northeast, both individuals are definitely female. Thanks for your help, Ed!

Copyright © 2013 Walter Sanford. All rights reserved.

Eastern Pondhawk dragonflies

May 14, 2013

The following slideshow features a couple of green Eastern Pondhawk dragonflies (Erythemis simplicicollis) spotted at two locations in Fairfax County, Virginia USA. Male Eastern Pondhawks are blue and females are green so these two dragonflies must be females, right? In a word, wrong.

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Do you see any difference between the two dragonflies? The dragonfly shown in Slide 1 is a mature female Eastern Pondhawk; Slide 2 shows an immature male. Look closely at the tip of the abdomen for both dragonflies: see a full-size version of Slide 1; and Slide 2. Notice the differences between male- and female terminal appendages, as shown in the following composite image: male appendages are shown in the background photo; female appendages are shown in the inset photo.

Eastern Pondhawk dragonfly (immature male)

Immature male (background photo) | Mature female (inset photo)

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”). Female dragonflies have a pair of cerci (superior appendages) that have little or no function.

Adult Eastern Pondhawk dragonflies exhibit sexual dimorphism: mature males are covered by blue pruinescence; females are green. The male Eastern Pondhawk’s green face distinguishes it from other similar-looking blue dragonflies. The following specimen was spotted at Accotink Bay Wildlife Refuge.

Eastern Pondhawk dragonfly (male)

Some species of dragonflies do not exhibit sexual dimorphism. Terminal appendages may be used to differentiate males and females for many types of dragonflies, such as Stream Cruisers (Didymops transversa).

Related Resources: Odonate Terminal Appendages.

Copyright © 2013 Walter Sanford. All rights reserved.

Brown Spiketail dragonfly (redux)

May 12, 2013

This Brown Spiketail dragonfly (Cordulegaster bilineata) has a face only a mother could love. Happy Mother’s Day!

Brown Spiketail dragonfly (female) Brown Spiketail dragonfly (female)

Copyright © 2013 Walter Sanford. All rights reserved.

Brown Spiketail dragonfly

May 7, 2013

The following photo gallery shows a Brown Spiketail dragonfly (Cordulegaster bilineata) perching near the ground. This individual is a female as indicated by its terminal appendages and spike-shaped ovipositor on the underside of its abdomen (posterior end).

This specimen was spotted in an open field along the trail to Hidden Pond, a small lake located at Meadowood Recreation Area in Fairfax County, Virginia USA.

Copyright © 2013 Walter Sanford. All rights reserved.


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