Posts Tagged ‘Big Bluet damselfly’

More predator/prey at Occoquan Bay

August 29, 2018

“Eat or be eaten” is perhaps the most fundamental law of nature. Predator-prey relationships can change suddenly: one minute a predator, such as a damselfly, is hunting for its next meal; next minute the damselfly becomes the prey and is a meal for another predator, such as a spider, elsewhere in the food web.

23 AUG 2018 | OBNWR | Black and Yellow Argiope (plus prey)

A Black and Yellow Argiope (Argiope aurantia) was spotted during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. A damselfly, possibly a Big Bluet (Enallagma durum), was trapped in the spider web.

Copyright © 2018 Walter Sanford. All rights reserved.

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The ugly side of Mother Nature

October 1, 2017

A Big Bluet damselfly (Enallagma durum) was spotted during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA. This individual is a male, eating a teneral damselfly.

10 SEP 2017 | Occoquan Bay NWR | Big Bluet (male, eating prey)

I think they may both be Big Bluets. Source Credit: Michael Moore, Virginia Odonata Facebook group.

Some species of odonates are cannibals, that is, they feed on their own species. And there it is — the ugly side of Mother Nature!

Copyright © 2017 Walter Sanford. All rights reserved.

Big Bluet damselfly (mating pairs)

September 3, 2017

Hundreds, if not thousands, of Big Bluet damselflies (Enallagma durum) were spotted on 30 August 2017 during a photowalk along Deephole Point Road at Occoquan Bay National Wildlife Refuge, Prince William County, Virginia USA.

A mating pair of Big Bluet was spotted “in heart.” The male is on the upper-right; the female on the lower-left.

30 AUG 2017 | OBNWR | Big Bluet (mating pair, “in heart“)

Big Bluet females are polymorphic, including a blue morph and brown morph. The female in this mating pair is a blue andromorph.

30 AUG 2017 | OBNWR | Big Bluet (mating pair, “in heart“)

I photographed the following male because he was perching at the right height for me to take the shot while standing. I took one photo before he flew to another perch, closer to the ground.

30 AUG 2017 | OBNWR | Big Bluet (male)

As it turns out, the single male led me to another mating pair of Big Bluet that I hadn’t noticed!

30 AUG 2017 | OBNWR | Big Bluet (mating pair, “in heart“)

The female in the preceding mating pair is a brown heteromorph. Color is a highly variable field marker, and describing color is subjective. In my experience, the heteromorph female Big Bluets native to Northern Virginia are light tan to light olive drab in color.

Copyright © 2017 Walter Sanford. All rights reserved.

More Big Bluet damselflies

December 24, 2016

More Big Bluet damselflies (Enallagma durum) were spotted in July 2016 during two photowalks along the Potomac River at Dyke Marsh Wildlife Preserve (DMWP).

More males

These individuals are males, as indicated by their blue and black coloration and by their terminal appendages.

Mating pair

The mating pair of Big Bluet damselflies shown in the following photograph is “in wheel,” in which the male uses “claspers” (terminal appendages) at the end of his abdomen to hold the female by her neck/thorax while they are joined at their abdomens. The male, blue and black in color, is on top; the female, green and black in color, is on the bottom.

The copulatory, or wheel, position is unique to the Odonata, as is the distant separation of the male’s genital opening and copulatory organs. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 377-378). Princeton University Press. Kindle Edition.

The wheel position is sometimes referred to as “in heart” when damselflies mate. In this case, the heart shape is deformed slightly.

A mating pair of Big Bluet damselflies (Enallagma durum) spotted at Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA. This pair is "in heart."

19 JUL 2016 | DMWP | Big Bluet (mating pair, “in tandem”)

The same pair is “in tandem” a while later: the male is on the right; the female is on the left. The male is engaged in “contact guarding,” in which the male and female fly “in tandem” to egg-laying sites. Contact guarding is used by some species of odonates to prevent aggressive males from hijacking the female.

A mating pair of Big Bluet damselflies (Enallagma durum) spotted at Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA. This pair is "in tandem."

19 JUL 2016 | DMWP | Big Bluet (mating pair, “in tandem”)

Look closely at the underside of the female’s abdomen, near the tip. Notice the ovipositor that she uses to insert eggs into vegetation (endophytic oviposition).

It’s helpful to take photos of mating pairs of damselflies, especially “in tandem,” since males and females of the same species can look quite different.

Sidebar: Scientific Classification of Damselflies

The following concise explanation of the scientific classification of damselflies is provided to help the reader understand where the genus Enallagma (American Bluets) fits into the bigger picture of the Order OdonataSuborder Zygoptera (Damselflies).

There are five families of damselflies in the United States of America, although only three families occur in the mid-Atlantic USA: Broad-winged damselflies; Narrow-winged damselflies (a.k.a., Pond Damselflies); and Spreadwing damselflies.

Family Calopterygidae is comprised of two genera.

Family Coenagrionidae is comprised of 14 genera. Three genera are common in Northern Virginia: Argia (Dancers); Enallagma (American Bluets); and Ischnura (Forktails).

Family Lestidae is comprised of two genera.

  • Archilestes (e.g., Great Spreadwing)
  • Lestes (e.g., Slender Spreadwing, Southern Spreadwing, Swamp Spreadwing)

There are relatively few genera of Broad-winged Damselflies and Spreadwing Damselflies. In contrast, there are many more genera and species of Narrow-winged Damselflies — more species, including many that look similar, makes this family the most challenging to learn!

Related Resources: Excellent digital scans created by Gayle and Jeanelle Strickland. Click on the button labeled “Download file” in order to view full-size version of the graphics.

  • Enallagma durum male #4 | male | JPG
  • Enallagma durum female #2 | female | JPG

Copyright © 2016 Walter Sanford. All rights reserved.

CSI: Dyke Marsh

December 22, 2016

You are looking at the scene of a brutal crime committed on 20 July 2016 at Dyke Marsh Wildlife Preserve. Look closely at the full-size version of the following photo. Do you see any forensic evidence that indicates what probably happened just before the photo was taken?

The preceding photo shows a Big Bluet damselfly (Enallagma durum) that was spotted along the Potomac River at Dyke Marsh Wildlife Preserve, Fairfax County, Virginia USA. This individual is a male, as indicated by his blue and black coloration and by his terminal appendages. Big Bluets prefer tidal bays and big rivers.

Related Resource: More Big Bluet damselflies is a blog post by Walter Sanford that features more photos of Big Bluet males as well as a mating pair.

Copyright © 2016 Walter Sanford. All rights reserved.

Blues for “Bluets”

July 12, 2015

Regular readers of my photoblog know I love me some odonates! Mostly, that is. Many American Bluets, members of the Pond Damsels Family of damselflies, can be difficult to identify, especially in the field. There are many species of bluets, most of them are blue, and many of them look similar. Yes, sometimes I get the blues when trying to identify bluets — no wonder I lovingly refer to them as “damnselflies!”

Five species of bluets are listed on the Friends of Huntley Meadows Park Odonata species list of damselflies: Familiar Bluet (Enallagma civile); Big Bluet (Enallagma durum); Stream Bluet (Enallagma exsulans); Skimming Bluet (Enallagma geminatum); and Orange Bluet (Enallagma signatum).

Orange Bluets, named for their orange-and-black coloration, are easy to identify and relatively common in the central wetland area at the park.

The fact of the matter is you’re unlikely to see more than one or two of the blue bluets on the species list, so there should be no need to curse my little friends in frustration because you’re unable to identify them. Look closely at the pattern of blue-and-black markings on the abdomen of males and you should be able to easily differentiate the three species of bluets featured in this post. Identifying females can be a lot more challenging.

Familiar Bluet

In my experience, the only blue bluet you’re likely to see in the central wetland area at Huntley Meadows Park (HMP) is Familiar Bluet (Enallagma civile).

Familiar Bluet damselfly (male, in flight)

15 SEP 2014 | HMP | Familiar Bluet (male, in flight)

Stream Bluet

Stream Bluets (Enallagma exsulans) are relatively common along some of the streams that flow through Huntley Meadows Park, such as Barnyard Run.

A Stream Bluet damselfly (Enallagma exsulans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

24 JUN 2015 | HMP | Stream Bluet (male)

It’s helpful to get shots of mating pairs in tandem, since males and females of the same species can look quite different.

A mating pair of Stream Bluet damselflies (Enallagma exsulans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem.

10 JUL 2015 | HMP | Stream Bluets (mating pair, in tandem)

Female Stream Bluets are polymorphic, displaying either green or blue on the thorax. The green morph appears in the two photos of a mating pair of Stream Bluets featured in this post.

A mating pair of Stream Bluet damselflies (Enallagma exsulans) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This pair is in tandem.

10 JUL 2015 | HMP | Stream Bluets (mating pair, in tandem)

Big Bluet

The author has never seen a Big Bluet damselfly (Enallagma durum) at Huntley Meadows Park. My theory is the wetlands at the park are the wrong habitat for Big Bluets.

Habitat Large sandy lakes and lower reaches of rivers, even extending into brackish estuaries. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 2156-2157). Princeton University Press. Kindle Edition.

It’s noteworthy that the only location where I have seen Big Bluets is Accotink Bay Wildlife Refuge (ABWR), and Ken Larsen’s photo of a Big Bluet (linked from the FoHMP Odonata species list) is from Occoquan Bay National Wildlife Refuge. Are you seeing the same pattern I see? The common keyword between our Big Bluet spottings is “bay.” Unless someone can show me a photograph of a Big Bluet spotted at Huntley Meadows Park, I feel strongly it should be deleted from the FoHMP Odonata species list.

A Big Bluet damselfly (Enallagma durum) spotted at Accotink Bay Wildlife Refuge, Fairfax County, Virginia USA. This individual is a male, shown eating an unknown insect.

17 SEP 2012 | ABWR | Big Bluet (male, eating prey)

The following poor quality photo is used to provide another illustration of the idea that it’s helpful to get shots of mating pairs in tandem, since males and females of the same species can look quite different. Female Big Bluets are polymorphic, displaying either brown or blue coloration. The brown morph is shown below.

A mating pair of Big Bluet damselflies (Enallagma durum) spotted at Accotink Bay Wildlife Refuge, Fairfax County, Virginia USA. This pair is in tandem.

10 SEP 2012 | ABWR | Big Bluet (mating pair, in tandem)

Related Resource: Dragonflies of Loudoun features a flight calendar for dragonflies and damselflies. Familiar Bluets are on the wing from July through September; Stream Bluets from May through August. Big Bluets aren’t listed. Hmmm, could it be because there aren’t any bays located in Loudoun County, Virginia?

Editor’s Note: The environment at Huntley Meadows Park may not be the ideal habitat for Skimming Bluet damselflies (Enallagma geminatum). The author has never seen a Skimming Bluet at the park, and the species isn’t linked from the FoHMP Odonata species list, suggesting Ken Larsen has never photographed one. If you have a photo of a Skimming Bluet at Huntley Meadows, then please contact me.

Copyright © 2015 Walter Sanford. All rights reserved.

Big Bluet damselfly (male, eating)

October 24, 2012

A Big Bluet damselfly (Enallagma durum) spotted along the shore of Accotink Bay. This individual is a male, as indicated by its blue coloration; it is shown eating a smaller winged insect.

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Habitat: Accotink Bay Wildlife Refuge, a 1,200 acre preserve located at Army Garrison Fort Belvoir, Fairfax County, Virginia USA.

Copyright © 2012 Walter Sanford. All rights reserved. www.wsanford.com


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