Archive for the ‘damselflies’ Category

Pop quiz answer key

June 9, 2017

Perhaps the simplest way to provide answers to the recent pop quiz — in which readers were challenged to identify the gender of two Southern Spreadwing damselflies (Lestes australis) — is to show what the teneral/immature male (shown in my last post) will look like when he’s a little older.

The following photos show Southern Spreadwings spotted at Mason Neck West Park, Fairfax County, Virginia USA. Both individuals are male, as indicated by their terminal appendages and blue coloration.

Both photographs of the male Southern Spreadwings were taken at an angle that shows their terminal appendages clearly.

All male damselflies have four terminal appendages, collectively called “claspers.” Male damselfly terminal appendages don’t look exactly the same for all species of damselflies, but their function is identical. Claspers are used to grab and hold female damselflies during mating: an upper pair of cerci (“superior appendages”) and a lower pair of paraprocts (“inferior appendages”).

In contrast, female damselflies have two cerci (sing. cercus), superior appendages that have little or no function. Notice the two “nubs” at the tip of the abdomen, as shown in the photo of the female Southern Spreadwing that was featured in the pop quiz.

Editor’s Notes: There are five families of damselflies (Suborder Zygoptera) in the United States of America, although only three families occur in the mid-Atlantic region: Family Calopterygidae (Broad-winged Damselflies)Family Coenagrionidae (Narrow-winged Damselflies); and Family Lestidae (Spreadwings).

Male Broad-winged Damselflies and Spreadwing Damselflies have terminal appendages that are large enough to see with the unaided eye. Generally speaking, both male and female Narrow-winged Damselflies are too small to see their terminal appendages clearly in most photographs.

Copyright © 2017 Walter Sanford. All rights reserved.

Pop quiz

June 7, 2017

OK, it’s time to assess what you’ve learned about damselflies by following my blog.

Two Southern Spreadwing damselflies (Lestes australis) were photographed on the same day at the same location. Both damselflies are teneral/immature, that is, they are relatively young. One is a female; one is a male. Can you identify the gender of the damselflies shown in the following photos?

I’ll give you a hint: Examine their terminal appendages by looking at the full-size version of both photos.

No. 1

No. 2

Editor’s Note: The answer key will be published in my next post.

Copyright © 2017 Walter Sanford. All rights reserved.

Voltinism, revisited

April 30, 2017

Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. Source Credit: Wikipedia.

Some species of odonates, such as Southern Spreadwing damselfly (Lestes australis), can be multivoltine.

Huntley Meadows Park

Long-term monitoring of a vernal pool at Huntley Meadows Park has shown Southern Spreadwing is multivoltine at that site.

Mason Neck West Park

Males and females from a single brood of Southern Spreadwing were observed during Fall 2016 at Mason Neck West Park; males from another brood were spotted at the same location on 05 April 2017 and again on 18 April 2017. This evidence suggests Southern Spreadwing is multivoltine at Mason Neck West Park (MNWP). Further field observations are necessary to determine whether more than two broods occur at this location.

This individual is a male, as indicated by his coloration and terminal appendages.

Please look at the full-size versions of the preceding photos in order to appreciate the “fresh” coloration that seems to be a noticeable characteristic for many species of recently-emerged odonates.

Copyright © 2017 Walter Sanford. All rights reserved.

Slender Spreadwing damselflies (females)

March 25, 2017

Two female Slender Spreadwing damselflies (Lestes rectangularis) were spotted during a photowalk around a vernal pool in the forest at Huntley Meadows Park.

No. 1

No. 2

Notice the second individual is bluer in color. Coloration is variable, so it’s better to look at other field markers when making an identification.

Copyright © 2017 Walter Sanford. All rights reserved.

Arachnids 2, Odonates 0

March 23, 2017

A spider was observed preying upon a teneral damselfly at a vernal pool in Huntley Meadows Park. The genus/species of the spider is uncertain; the damselfly appears to be a female Slender Spreadwing (Lestes rectangularis).

31 MAY 2016 | Huntley Meadows Park | spider preying upon damselfly

According to experts on the BugGuide Facebook group, the spider is probably an unknown species from the Family Araneidae (Orb Weavers).

Post Update: Ashley Bradford, a local arachnid expert and excellent all-around amateur naturalist, identified the spider as an Arabesque Orbweaver (Neoscona arabesca). Thanks, Ashley!

31 MAY 2016 | Huntley Meadows Park | spider preying upon damselfly

Aperture Priority mode was used for the next photo, in order to increase the depth of field. As you can see, the depth of field at f/8.0 was insufficient for both the damselfly and spider to be in focus.

31 MAY 2016 | Huntley Meadows Park | spider preying upon damselfly

A dragonfly was trapped in a spider web at Hidden Pond, Meadowood Recreation Area, Fairfax County, Virginia USA. The dragonfly, possibly an immature male Blue Dasher (Pachydiplax longipennis), is infested with parasitic red water mites.

22 JUN 2016 | Meadowood Recreation Area | dragonfly in spider web

Copyright © 2017 Walter Sanford. All rights reserved.

How to Identify Damselfly Exuviae to Family

March 11, 2017

There are five families of damselflies (Suborder Zygoptera) in the United States of America, although only three families occur in the mid-Atlantic region: Family Calopterygidae (Broad-winged Damselflies)Family Coenagrionidae (Narrow-winged Damselflies); and Family Lestidae (Spreadwings).

Pattern recognition can be used to tentatively identify damselfly larvae/exuviae to the family level: the shape of the prementum is characteristic for each of the three families; mnemonics can be used to remember each distinctive shape.

Family Calopterygidae (Broad-winged Damselflies)

Family Calopterygidae features a prementum with a shape that looks somewhat similar to Family Coenagrionidae. Look for an embedded raindrop shape, located toward the upper-center of the prementum.

An Ebony Jewelwing damselfly (Calopteryx maculata) exuvia was collected along a small stream located in eastern Fairfax County, Virginia USA.

Family Calopterygidae (Broad-winged Damselflies) | prementum

Family Coenagrionidae (Narrow-winged Damselflies)

The shape of the prementum for Family Coenagrionidae reminds me of a keystone.

A Narrow-winged Damselfly exuvia — probably Argia sp. (it’s a work in progress) — was collected along the Potomac River in Fairfax County, Virginia USA. This individual is a female, as indicated by the rudimentary ovipositor located on the ventral side of her abdomen.

Family Coenagrionidae (Narrow-winged Damselflies) | ventral

The lamellae, also known as caudal lamellae, are external structures used by damselfly larvae for both respiration and locomotion. In contrast, the respiratory system for dragonfly larvae is internal. Characteristics of the caudal lamellae (including shape of/patterns on) are some of the clues that can be used to identify damselflies to the genus/species level.

Family Lestidae (Spreadwings)

The unique shape of the prementum for Family Lestidae reminds me of a rattle (musical instrument).

A damselfly exuvia from the Family Lestidae (Spreadwings) was collected from a small vernal pool located in eastern Fairfax County, Virginia USA. Although the genus/species is unknown (again, it’s a work in progress), both Slender Spreadwing (Lestes rectangularis) adults and Southern Spreadwing (Lestes australis) adults were observed at the vernal pool on the same day this specimen was collected.

Family Lestidae (Spreadwings) | prementum

Related Resources: The first step is the hardest, as the saying goes. In this case, it’s easier to identify damselfly larvae/exuviae to the family level than it is to identify specimens to the genus/species level. There are relatively few resources, especially online resources. The following links to two dichotomous keys and a pattern-matching guide for caudal lamellae should help you get started. Many of the same species of damselflies that are known to occur in Michigan, Florida, and the Carolinas can be found in the mid-Atlantic region.

Copyright © 2017 Walter Sanford. All rights reserved.

Acceptable uncertainty

February 23, 2017

An unknown species of damselfly from the Family Coenagrionidae (Narrow-winged Damselflies) was spotted at the stormwater management pond located at Mason Neck West Park. This individual is a female, as indicated by her terminal appendages.

I thought the damselfly might be a mature female Rambur’s Forktail damselfly (Ischnura ramburii), based upon the fact that I’d seen an immature female Rambur’s Forktail on 03 October 2016 at the same location. I consulted the experts of the Northeast Odonata Facebook group for verification of my tentative identification.

It’s a female bluet, probably Familiar [Bluet] but it has a hint of a carina, so it might be Big [Bluet], but the eyespots look more like Familiar. Female Rambur’s does not have shoulder stripes. Source Credit: Dr. Michael Moore. Michael is an active contributor to the Dragonfly and Damselfly Field Guide and ID App.

Difficult though it may be for me to accept, sometimes it’s impossible to identify odonates with certainty based upon a single photograph. This is especially true for many species of female damselflies.

Copyright © 2017 Walter Sanford. All rights reserved.

More power!

February 19, 2017

Like Tim “The Tool Man” Taylor, I like more power. (Grunt, grunt.) Actually, I need more power for some of the macro photography that I do, especially when I’m shooting small specimens such as odonate exuviae.

For the past few months, I’ve experimented with several ways to get more “oomph” from my Canon EF100mm f/2.8L Macro lens. I’ve tested three types of photo gear used in combination with the macro lens including extension tubes, a close-up filter, and a tele-extender.

The first photograph shows the following equipment, from left-to-right: Canon EOS 5D Mark II digital camera; Canon Extender EF 1.4x II (white); Kenko 20mm macro automatic extension tube; Canon EF100mm f/2.8L Macro lens; 67-52mm step-down ring; 52-42mm step-down ring; Raynox DCR-250 close-up filter (covered by lens cap).

Canon EOS 5D Mark II macro photography kit.

Canon EOS 5D Mark II macro photography kit.

For most macro subjects, my “base kit” includes the 100mm macro lens plus a 20mm extension tube. Adding one or more extension tubes reduces the minimum focusing distance of the lens. Adding a close-up filter enables me to zoom in closer to the subject. The tele-extender effectively changes the focal length of the macro lens from 100mm to 140mm, resulting in a 1 f/stop loss of light. Some photographers contend that adding a tele-extender can result in a loss of sharpness. Your results may vary from mine, but I find the increased magnification that results from using a tele-extender is worth a small loss of sharpness.

The Canon Extender EF 1.4x II is incompatible with the Canon EF100mm f/2.8L Macro lens — it is impossible to connect the two devices directly. It’s worth noting that incompatible doesn’t mean they don’t work together — they do, as long as an extension tube is added in-line between the tele-extender and lens.

The last photograph shows the following equipment, couterclockwise from the upper-left: “snap-on universal adapter” for Raynox DCR-250 close-up filter; Raynox close-up filter mounted on a 52-43mm step-down ring; and a 67-52mm step-down ring.

Several mounting adapters for Raynox DCR-250 close-up filter.

Several mounting adapters for Raynox DCR-250 close-up filter.

The Raynox DCR-250 close-up filter comes with a “snap-on universal adapter” for mounting the filter on lenses with a filter size from 52-67mm. The adapter clips on the front of a lens the same as a lens cap. In my opinion, that’s OK for use in a home photo studio but less than ideal for use in the field.

I bought two inexpensive step-down rings that can be used to mount the close-up filter more securely: a 52-43mm step-down ring enables me to mount the Raynox DCR-250 on either the “Nifty 50” (a 50mm lens for my Canon DSLR) or Panasonic DMC-FZ150 superzoom bridge camera, my go-to kit for photowalking; a 67-52mm step-down ring enables me to connect the 52-43mm/Raynox close-up filter combo (shown above) with my Canon 100mm macro lens.

In case you’re wondering whether vignetting is a problem when using two step-down rings with the Canon 100mm macro lens, it isn’t. As it turns out, the front lens element is recessed quite a bit from the lens barrel so the step-down rings cover little if any glass.

Related Resources:

Afterthoughts

Two thoughts occurred to me after this post was published.

  1. As a result of limited testing, I concluded that it is possible to stack two or three extension tubes in order to achieve the same result as using a tele-extender without any loss of sharpness. Problem is, the minimum focusing distance is so small that the working distance between the lens and subject is too close for comfort. Adding the tele-converter provides more magnification at a slightly longer working distance.
  2. Caution: Connect the 52-43mm step-down ring to the 67-52mm step-down ring BEFORE connecting the combo to the 100mm macro lens. Otherwise there is some risk of scratching the front element of the macro lens.

Copyright © 2017 Walter Sanford. All rights reserved.

American Rubyspot damselfly (male)

January 24, 2017

An American Rubyspot damselfly (Hetaerina americana) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a male, as indicated by his coloration and hamules.

One and done. That’s the way some wildlife photographers shoot a subject. I like to “work the shot,” that is, shoot the subject from all angles and in different positions.

In this case, the damselfly was perching over deep water. I waded into the water as far as I could go in my knee-high green wellies and made the best of a less than ideal situation.

Since the subject never moved from his perch above the water, I moved so that my viewpoint featured different backgrounds. Also, the damselfly changed position slightly during the shoot. Although all of the photos in this set are similar, each one is different in the way it looks and feels.

Copyright © 2017 Walter Sanford. All rights reserved.

Blue-fronted Dancer damselfly (female)

January 18, 2017

Blue-fronted Dancer damselfly (Argia apicalis) was spotted during a photowalk along Accotink Creek Trail at Accotink Bay Wildlife Refuge (ABWR), Fairfax County, Virginia USA. An old wooden boardwalk is located near the terminus of the trail.

A Blue-fronted Dancer damselfly (Argia apicalis) spotted along Accotink Creek at Accotink Bay Wildlife Refuge, Fairfax County, Virginia USA. This individual is a female.

07 AUG 2016 | ABWR | Blue-fronted Dancer (female andromorph)

This individual is a female andromorph, as indicated by her coloration and terminal appendages. Females have a noticeably thicker abdomen than males.

Female Blue-fronted Dancers are polymorphic: andromorph females are blue like males; heteromorph females are brown. Andromorph females tend to be a lighter shade of blue than males of the same species, and do not feature the same blue coloration as males on abdominal segments eight, nine, and 10 (S8-10).

A Blue-fronted Dancer damselfly (Argia apicalis) spotted along Accotink Creek at Accotink Bay Wildlife Refuge, Fairfax County, Virginia USA. This individual is a female.

07 AUG 2016 | ABWR | Blue-fronted Dancer (female andromorph)

The taxonomic classification of Blue-fronted Dancer is as follows: Order Odonata (Dragonflies and Damselflies); Suborder Zygoptera (Damselflies); Family Coenagrionidae (Narrow-winged Damselflies); Genus Argia (Dancers); Species apicalis.

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.

Editor’s Note: This is the first female Blue-fronted Dancer that I’ve seen/photographed. Thanks to Michael Moore and Ed Lam, members of the Northeast Odonata Facebook group, for verifying my tentative identification. Dr. Michael Moore is an active contributor to the Dragonfly and Damselfly Field Guide and ID App; Ed Lam is author and illustrator of Damselflies of the Northeast.

Copyright © 2017 Walter Sanford. All rights reserved.


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