Archive for September, 2015

Robber Fly eating a Yellowjacket

September 30, 2015

While exploring the “northern wetland” at Huntley Meadows Park, a pair of insects landed on my upper thigh: a female Red-footed Cannibalfly (Promachus rufipes), a species of Robber Fly (Family Asilidae), eating a Yellowjacket (Vespula sp.). The pair was too close to photograph, so I gently “shooed” them away — fortunately they landed on a nearby cattail leaf!

A Red-footed Cannibalfly (Promachus rufipes), a species of robber fly (Family Asilidae), eating a Yellowjacket (Vespula sp.) at Huntley Meadows Park, Fairfax County, Virginia USA.

23 SEP 2015 | Huntley Meadows Park | Robber Fly eating a Yellowjacket

Robber Flies feed mainly on other insects.

The fly attacks its prey by stabbing it with its short, strong proboscis injecting the victim with saliva containing neurotoxic and proteolytic enzymes which very rapidly paralyze the victim and soon digest the insides; the fly then sucks the liquefied material through the proboscis. Source Credit: Asilidae, from Wikipedia.

A Red-footed Cannibalfly (Promachus rufipes), a species of robber fly (Family Asilidae), eating a Yellowjacket (Vespula sp.) at Huntley Meadows Park, Fairfax County, Virginia USA.

23 SEP 2015 | Huntley Meadows Park | Robber Fly eating a Yellowjacket

Thanks to BugGuide Facebook group members James W. Beck for verifying my identification of the Robber Fly, and to Ian Kho for definitely identifying the genus of Yellowjacket and tentatively identifying its species.

[The] Yellowjacket is in the genus Vespula. Mostly yellow face suggests V. maculifrons/flavopilosa. Source Credit: Ian Kho.

Copyright © 2015 Walter Sanford. All rights reserved.

Electrofishing for Northern Snakehead

September 28, 2015

Northern Snakehead (Channa argus) is an exotic species of fish (non-native) that threatens to disrupt the marshland ecosystem at Huntley Meadows Park, Fairfax County, Virginia USA.

I think that it is safe to say they are here to stay, after seeing the numbers of fish we removed from the wetland this past summer [2014]. We have to accept that they are here, but we will do our best to manage the populations and keep their influence on our delicate ecosystem as small as possible. Source Credit: David M. Lawlor, Natural Resource Manager, Huntley Meadows Park. Staff Manages Snakehead Threat At Huntley Meadows Park.

On 25 September 2015, Dave Lawlor (shown below, far right) collaborated with a team of staff members from the Fairfax County Department of Public Works and Environmental Services to electrofish for Northern Snakehead in the central wetland area at the park.

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

The process seemed to be all about teamwork: every member performed a role, beginning with the “electroshockers” (see close-up, shown below) working closely with the “herders” and “dip-netters,” and ending with the “collectors.” [Editor’s Note: Words in quotes are my unofficial terms for each of the roles on the electrofishing team.]

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

The following photo shows a relatively large Northern Snakehead netted near the berm. Approximately 25 snakeheads were culled from the wetlands, including several measuring at least 18 inches (18″) in length! The entrails will be examined to collect data about the diet of these predatory fish.

A Northern Snakehead (Channa argus) netted in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

A Northern Snakehead netted in the central wetland area.

The next photo shows Dave Lawlor (shown left) working closely with one of two “electroshockers” in search of snakeheads hunkered down for cover underneath a fallen log.

Electrofishing for Northern Snakehead (Channa argus) in the central wetland area at Huntley Meadows Park, Fairfax County, Virginia USA.

Electrofishing for Northern Snakehead at Huntley Meadows Park.

Coincidentally, an artificial fishing lure was observed along the shoreline not far from the location of the preceding photo. Fishing is not permitted at Huntley Meadows Park. If you see anyone fishing illegally, please call the HMP Visitor Center at 703-768-2525.

An artificial fishing lure spotted at Huntley Meadows Park, Fairfax County, Virginia USA.

An artificial fishing lure.

Related Resources:

Editor’s Note: Mike Powell and I were fortunate to be in the right place when the electrofishing team arrived at the central wetland area; with permission from Dave Lawlor, we enjoyed the extraordinary opportunity to photograph this interesting event. See Mike’s excellent blog post: Snakeheads at Huntley Meadows Park.

Copyright © 2015 Walter Sanford. All rights reserved.

Roseate Skimmer dragonfly (male)

September 26, 2015

Breaking news: I discovered a new species of dragonfly at Huntley Meadows Park — a Roseate Skimmer dragonfly (Orthemis ferruginea). This is the first official record of Orthemis ferruginea in Fairfax County, Virginia.

Actually, I discovered this species last year but was unable to shoot a photo to prove I wasn’t hallucinating pink dragonflies! On 10 September 2014, I spotted a male Roseate Skimmer that made one patrol around a pool near an old beaver lodge (one that overlapped the boardwalk that goes through the central wetland area), landed for one second (no kidding) and flew upstream along Barnyard Run; I never saw it again. This year, I have photographic proof.

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

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Dig that crazy metallic purple face!

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

After one spotting, I was willing to dismiss the 2014 Roseate as a transient species; after two spottings, I’m beginning to wonder whether there’s a small reproducing population at Huntley Meadows Park. Perhaps I’m guilty of wishful thinking, but some of the marks on the dragonfly’s abdomen look like scratches from mating.

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Look to the left…

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Look to the right. Stand up, sit down, fight, fight, fight! Huh? I repurposed a cheer for my old high school football team since it seems to appropriately describe the male Roseate’s aggressive behavior whenever males of other species invaded his space.

A Roseate Skimmer dragonfly (Orthemis ferruginea) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

23 SEP 2015 | Huntley Meadows Park | Roseate Skimmer (male)

Roseate Skimmers are common at tropical latitudes; they are uncommon to rare in the middle latitudes.

These have been working their way north but they are rare … in our area.  I have a record at the National Arboretum in Washington, D.C. in 1998, and two were found in Howard County, Maryland in 1999. Source Credit: Richard Orr, renowned expert on odonates of the mid-Atlantic region of the United States.

I’ve never seen a Roseate Skimmer but am aware of three (3) previous records for Virginia. Source Credit: Steven M. Roble, Ph.D., Staff Zoologist, Virginia Department of Conservation and Recreation, Division of Natural Heritage.

Related Resource: Roseate Skimmer (Othemis ferruginea) spotted in Henrico County, Virginia by Allen Bryan.

Copyright © 2015 Walter Sanford. All rights reserved.

Depth of Field

September 24, 2015

A quote from one of the blogs I follow reminded me of the limitations of depth of field in photography, especially wildlife photography.

One final note: The above does not hold water when you are working anywhere near the lens’s minimum focus distance where d-o-f is measured in small fractions of a single inch. The lesson is that d-o-f increases dramatically as the distance to the subject increases. Source Credit: Fast Thinking Rescues Triplets! – A Depth of Field Lesson, by Arthur Morris/Birds as Art.

Depth of field decreases as the distance to a subject decreases and as focal length increases. When photographing odonates, I always try to get as close as possible. I like to work at (or near) the closest focusing distance of my camera lens and at maximum zoom. As a result, depth of field is always shallow and always a concern.

Sample Photo

For example, let’s look at a photograph of a male Blue-faced Meadowhawk dragonfly (Sympetrum ambiguum) taken during a photowalk at Huntley Meadows Park on 06 September 2015.

A Blue-faced Meadowhawk dragonfly (Sympetrum ambiguum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

ISO 100 | 108mm | -1 ev | f/5.2 | 1/800

Look closely at the full-size version of the preceding photo. Notice the head of the dragonfly is in tack-sharp focus, the thorax is acceptably in focus, and the abdomen is out of focus. The following depth of field table — calculated specifically for my Panasonic Lumix DMC-FZ150 superzoom bridge camera set for maximum focal length — tells the story. (Note: The entire range of f-stop values for my camera is highlighted by the red rectangle; the range of f-stop values at maximum focal length is highlighted by the green rectangle.)

The f-stop number for my photograph is f/5.2, according to its metadata. f/5.6 is the closest value shown in the preceding table of f-stops (in increments of one full stop of exposure). At f/5.6 and a distance of six feet (6′) — the approximate closest focusing distance at maximum zoom — the total depth of field is 0.6 inches (0.6″), or 1.525 cm (15.2 mm).

Two features in Apple Aperture that I miss in Abobe Lightroom are the ability to display the autofocus points used to capture a photograph, and the loupe tool that can be used to check the focus of images.

The following screen capture shows a single focus point that was nearly centered on the dragonfly’s face. This is the single plane in which the photo is perfectly focused.

Show-Focus-Points

Apple Aperture | Show Focus Points

Blue-faced Meadowhawks are relatively small dragonflies, averaging 36-38 mm in length. Measuring 7.5 mm from the face of the dragonfly takes us to a point about one-fifth (1/5) of the way along the length of its body, probably near the thorax/abdomen boundary; beyond that point the dragonfly’s abdomen is noticeably out of focus, as shown in the following screen capture of the loupe tool.

Screen-Shot_2015-09-22_at-6.06.59PM

Apple Aperture | Focus Loupe

You may be thinking, “Hey, I thought you said the total depth of field is ~15 mm.” That’s true, but the total depth of field is divided approximately 50/50 on either side of the single plane of perfect focus. The fact of the matter is I wasted half of the available depth of field by focusing on the dragonfly’s eyes. Although it would have been better to focus on the thorax, it was difficult to ignore the number one rule of wildlife photography: If the eyes aren’t in focus, then the photo isn’t a keeper. Making lemonade from lemons, at least the photo doesn’t look flat!

Application

The following photograph of a toy dragonfly purchased from the Visitor Center at Huntley Meadows Park helps to illustrate the limitations of depth of field when photographing odonates. The toy dragonfly is approximately 70 mm in length from head-to-tail — a little smaller than a typical Great Blue Skimmer dragonfly, averaging 56-63 mm in length.

Remember, at f/5.6 and a distance of six feet, the depth of field for my Panasonic camera is 0.6 inches (0.6″), or 1.525 cm (15.2 mm) — that’s less than one-fourth of the length of the toy dragonfly’s body!

Decreasing the aperture to f/8 (the f-stop number gets larger) increases the depth-of-field to 0.8 inches (0.8”), or 2.032 cm (20.3 mm) but that’s still less than a third of the body length.

Dragonfly toy, purchased from Visitor Center, Huntley Meadows Park, Fairfax County, Virginia USA.

~70 mm long (~7 cm), or ~2.76 in

So what’s the take-away from this post? Always be mindful of depth of field and choose camera settings, focus points, and viewing angles that will maximize what appears to be acceptably in focus.

Copyright © 2015 Walter Sanford. All rights reserved.

Ethical or unethical?

September 22, 2015

To Photoshop, or not to Photoshop, that is the question. Both the question and the answer aren’t as simple they may seem at face value. In essence, the question asks whether it’s acceptable to manipulate a photo in any way. I think every answer is a matter of personal opinion based upon individual ethical standards. More about that at the end of this post. For now, let’s look a specific case.

A recent blog post entitled Unusual viewpoints featured two photos of a female Halloween Pennant dragonfly (Celithemis eponina) spotted in a field located near Dogue Creek at Huntley Meadows Park. Before I published the post, I considered using Photoshop to remove some distracting elements in one of the photos; I decided to publish the photo “as is.”

BEFORE

The cluster of grasses in the lower-right corner of the photograph reminds me of exploding fireworks. Go figure! Point being, I think the grass cluster detracts from the photograph more than it contributes. The more I looked at the photo, the more I knew the distracting elements had to go.

A Halloween Pennant dragonfly (Celithemis eponina) spotted near Dogue Creek, Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female with a mild infestation of black water mites.

Aspect Ratio: Original Aspect Ratio (4 x 3)

AFTER

So I did what needed to be done: the distracting elements were removed; the image was reformatted to a 2 x 3 aspect ratio, a better fit for the Photoshopped version of the photo.

A Halloween Pennant dragonfly (Celithemis eponina) spotted near Dogue Creek, Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female with a mild infestation of black water mites.

Aspect Ratio: 2 x 3 (4 x 6)

I know which version I like better. Which one do you prefer, Before or After? Before choosing a favorite, I recommend viewing the full-size version of each photo.

Ethical Considerations

Back to the ethical question posed at the beginning of this post. Here’s how I rationalize removing the distracting elements. When shooting photos in the field, who among us hasn’t either moved or removed a blade of grass, etc. for better composition? If I had three arms and thought I could have moved the grass cluster without spooking the dragonfly, then I would have done it. Essentially that’s all I did, only I did it during post-processing. And more importantly, I did nothing to alter the dragonfly itself.

Is it OK to straighten and crop a photo? Is it OK to adjust white balance, exposure, color, contrast, etc.? Is it OK to reduce noise and sharpen images? Most photographers would answer “Yes, yes, yes!” In my opinion, Photoshop is just another tool in a photographer’s toolbox, albeit one used best with some restraint.

In the interest of full disclosure, whenever “Photoshop” is listed among the categories for one of my photoblog posts, then the reader knows Photoshop is one of the tools used during the creative process.

Related Resource: Odonart Portfolio.

Copyright © 2015 Walter Sanford. All rights reserved.

Dashing Blue Dasher

September 20, 2015

In a recent blog post, I wrote about seeing the beauty in a common dragonflyBlue Dasher dragonflies (Pachydiplax longipennis) are so ubiquitous in the wetlands of Huntley Meadows Park, it’s easy to get desensitized to their beauty.

A Blue Dasher dragonfly (Pachydiplax longipennis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

10 JUL 2015 | Huntley Meadows Park | Blue Dasher (male)

This individual is a handsome male, as indicated by his coloration and terminal appendages. He posed for me when I stopped to rest during an “extreme photowalk” with Michael Powell. Actually, the male Blue Dasher was posing for females looking for a mating partner.

The coffee-colored water in the background — the result of recent heavy rainfall — enabled me to create a photo with a clean, uncluttered background that focuses the viewer’s attention on the subject, as it should be. The water color also complements the coloration of the dragonfly.

Related Resource: Odonart Portfolio.

Copyright © 2015 Walter Sanford. All rights reserved.

The exposure triangle and exposure compensation

September 18, 2015

What if I wanted to set my Panasonic Lumix DMC-FZ150 superzoom bridge camera for less light sensitivity (low ISO) with a relatively fast shutter speed and the smallest possible aperture — impossible, right? After all, the lens diameter is smaller than many DSLR telephoto zoom lenses (therefore it has less light-gathering power) and there’s a lot of glass inside the 600mm equivalent lens.

If you understand the “exposure triangle” and how “exposure compensation” affects exposure, then you know it is do-able. Here’s how it works.

Background

Every time ISO is doubled (or halved), that’s one full “stop” of exposure. For example, changing ISO from 100 to 200 is plus one stop. The same is true for both aperture and shutter speed. For example, decreasing the aperture from f/5.6 to f/8 is minus one stop, and halving the shutter speed from 1/250s to 1/500s is minus one stop. A list of full stops for ISO, aperture, and shutter speed is shown below.

  • ISO: 50, 100, 200, 400, 800, 1600, 3200, 6400, etc.
  • Aperture: 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45, 64, etc.
  • Shutter speed: 1/1000s, 1/500s, 1/250s, 1/125s, 1/60s, 1/30s, 1/15s, 1/8s, 1/4s, 1/2s, 1s, etc.

Exposure Triangle

If you set your camera for one of the auto modes (e.g., Program Mode) and Auto ISO, then every setting in the “exposure triangle” is a wildcard and anything can happen.

If you want more control over how a picture turns out, then the goal is to control two of the three variables in the exposure triangle. For example, when using my Panasonic superzoom camera I prefer to shoot in shutter priority auto-exposure mode in order to avoid “camera shake.” Typically the camera is set for ISO 100 at a shutter speed of 1/800s — the camera decides which aperture to use. But wait, you still have some control over aperture!

Exposure Compensation

Suppose I use the same camera settings listed above, but also set the camera for minus one “exposure compensation” (-1 ev). This reduces the amount of light reaching the sensor by one full stop of exposure. The camera can’t change either the ISO or shutter speed, so what’s left to change? The only thing the camera can do is decrease the aperture (which means the f-stop number gets bigger) so the aperture will decrease by one full stop. For example, if the camera selected f/5.6 and I selected -1 ev, then the aperture will be f/8, resulting in more depth of field (something I usually want). How cool is that?

Sample Photos

I shot photo sets of eight different male Blue-faced Meadowhawk dragonflies (Sympetrum ambiguum) during a photowalk at Huntley Meadows Park on 06 September 2015.

Male 1: Spot metering with a single focus point on lower half of thorax.

A Blue-faced Meadowhawk dragonfly (Sympetrum ambiguum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

ISO 100 | 108mm | 0 ev | f/5.2 | 1/800s

The preceding photo looks great, right? Look closely at the full-size version of the photo. Notice the focus is tack-sharp for the dragonfly’s head and thorax, but softer for the terminal appendages at the tip of its abdomen. That’s a no-no for someone like me with a fixation on terminal appendages! Usually I wouldn’t publish a photo like this one, but it clearly illustrates what can happen when the depth-of-field is too shallow for a given point of view.

Male 8: Spot metering with a single focus point on upper half of thorax.

A Blue-faced Meadowhawk dragonfly (Sympetrum ambiguum) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

ISO 100 | 108mm | -1.66 ev | f/8 | 1/800s

In contrast with the photo of Male 1, notice the photo of Male 8 is tack-sharp from head-to-tail. The camera settings for ISO and shutter speed are the same for both photos, so what caused the latter photo to turn out better than the former? Notice the setting for exposure compensation is nearly minus two full stops, resulting in a decrease in the aperture of more than one full stop (f/8 is the maximum aperture for the DMC-FZ150).

Low ISO with a relatively fast shutter speed at the smallest possible aperture — just what the doctor ordered and all made possible by understanding the exposure triangle and the effect of exposure compensation on exposure. I’ll say it again. How cool is that?

Afterthoughts

Realize that some of the “magic” happens because I almost always use an external flash unit. And I always shoot “RAW” photos because that format enables maximum flexibility during post-processing.

And by now you should realize that knowing about the one-stop rule and the exposure triangle has wide-ranging application, e.g., how to set your camera using Manual Mode.

Plus it’s worth noting this is how program shift works when using “Program Mode.” After metering a shot, program shift can be used to select equivalent combinations of aperture and shutter speed. For example, if you increase the aperture by one full stop (the f-number get smaller) then the shutter speed will decrease by one full stop (the denominator gets larger and the time value decreases). Make sense?

Remember, experimentation is the best teacher — that’s how I learned almost everything I know about photography!

Related Resources:

Copyright © 2015 Walter Sanford. All rights reserved.

Unusual viewpoints

September 16, 2015

A single Halloween Pennant dragonfly (Celithemis eponina) was spotted in a field located near Dogue CreekHuntley Meadows Park (HMP). This individual is a female, as indicated by its coloration and terminal appendages; no males were spotted during the photowalk.

A Halloween Pennant dragonfly (Celithemis eponina) spotted near Dogue Creek, Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female with a mild infestation of black water mites.

10 JUL 2015 | HMP | Halloween Pennant (female)

The photos in this set were taken on a very windy day. The wind was blowing so hard the dragonfly struggled to hold onto her perch, as shown in the next photo when the pennant was almost flipped upside-down.

Notice the dragonfly has a mild infestation of parasitic black water mites.

A Halloween Pennant dragonfly (Celithemis eponina) spotted near Dogue Creek, Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a female with a mild infestation of black water mites.

10 JUL 2015 | HMP | Halloween Pennant (female)

(See a full-size version of the preceding photo, without annotation.)

Digital Dragonflies: presenting high-resolution digital scans of living dragonflies.

  • Genus Celithemis | Celithemis eponina | Halloween Pennant | female | top view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | female | side view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | male | top view
  • Genus Celithemis | Celithemis eponina | Halloween Pennant | male | side view

Copyright © 2015 Walter Sanford. All rights reserved.

A Southern Fortnight, Part 7 – “Arty”

September 14, 2015

The Backstory: A Southern Fortnight

For the first two weeks during May 2015, Southern Spreadwing damselflies (Lestes australis) were observed at a vernal pool and nearby drainage ditch in the forest at Huntley Meadows Park. I spotted approximately six males and several females during the fortnight. Their sudden disappearance seemed to coincide with a population explosion of Eastern Pondhawk dragonflies (Erythemis simplicicollis) in mid-May. Eastern Pondhawks, especially females, are voracious predators with a penchant for preying upon damselflies.


Alas, all good things must come to an end. This is the last post in what turned out to be a seven-part series called “A Southern Fortnight.” But don’t be sad because I saved some of the better photos for last! The male Southern Spreadwing featured in this post had a preference for perching in front of colorful vegetation that enabled me to capture shots of the damselfly sharply-focused against beautiful bokeh backgrounds, while he waited patiently for a mating partner to join him.

In order to avoid “camera shake” when using my Panasonic Lumix DMC-FZ150 superzoom bridge camera, I prefer to shoot in shutter priority auto-exposure mode. The rule-of-thumb for tack-sharp photos recommends a shutter speed that is equal to or greater than the reciprocal of the lens focal length (actual focal length for full-frame sensor cameras or 35mm equivalent for crop sensor cameras), in my case, no less than 1/800s for a 600mm equivalent telephoto lens. The following photo was shot in shutter priority mode: ISO 100 | 108mm/600mm | f/5.2 | 1/1000s | 0 ev.

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

08 MAY 2015 | HMP | Southern Spreadwing (male)

Whenever the subject is as cooperative as this one and I have the luxury of time, I will shoot some photos in aperture priority auto-exposure mode in order to get greater depth-of-field. At a smaller aperture, the camera will often select a relatively slow shutter speed so it is essential to hold the camera rock-steady and that usually means using a tripod. In this case, I was sitting on my Coleman camp stool with my elbows resting on my knees. The following photo was shot in aperture priority mode: ISO 100 | 108mm/600mm | f/7.1 | 1/160s | 0 ev.

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

08 MAY 2015 | HMP | Southern Spreadwing (male)

Notice the terminal appendages are out of focus in the following photo. Usually I wouldn’t publish a photo like this one, but decided to make an exception since it’s the only photo in this set that shows both the damselfly’s light-blue face and his hamules. The male’s claspers are clearly in focus in the four other photos.

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

08 MAY 2015 | HMP | Southern Spreadwing (male)

Although the last two photos show the damselfly in nearly the same pose, I chose to use both images due to subtle variations in the coloration of the background.

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

08 MAY 2015 | HMP | Southern Spreadwing (male)

A Southern Spreadwing damselfly (Lestes australis) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. This individual is a male.

08 MAY 2015 | HMP | Southern Spreadwing (male)

Related Resources:

Copyright © 2015 Walter Sanford. All rights reserved.

Odonate exuviae (in situ)

September 12, 2015

Odonates are aquatic insects that spend most of their life as larvae that live in water; this stage of their life cycle can last from a few months to a few years. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

Careful and/or lucky observers will notice exuviae (sing. exuvia), also known as either “cast skins” or “shed skins,” left behind when odonate larvae emerge.

The first three photographs show exuviae of odonates that emerged from the bioswale at the head-end of the Hike-Bike Trail at Huntley Meadows Park.

The flash/no-flash debate is settled in my mind, as evidenced by the preceding two-image gallery of photos. Although the photo shown on the left may have a more natural or “artier” look, critical detail is lost in the shadows, including the Long-jawed Orb Weaver (Family Tetragnathidae) lurking in the darkness on the left-most cattail rush!

The next photo shows cast skins from two different species of odonates. Most experts agree it is virtually impossible to identify exuviae to the species level using only photographs, although some cast skins are so distinctive it is possible to identify the family from a photo.

Two odonate exuviae (genus/species unknown) spotted at Huntley Meadows Park, Fairfax County, Virginia USA. These individuals emerged from the bioswale at the head-end of the Hike-Bike Trail.

05 AUG 2015 | HMP | two odonate exuviae (genus/species unknown)

The last photograph shows a cast skin spotted in the central wetland area, near beginning of boardwalk.

An odonate exuvia (genus/species unknown) spotted at Huntley Meadows Park, Fairfax County, Virginia USA.

21 AUG 2015 | HMP | odonate exuvia (genus/species unknown)

Related Resources: Be forewarned — identification of odonate larvae is difficult at best and impossible at worst. If you enjoy a challenge, then here are a few free resources that should be helpful.

Editor’s Note: Collecting specimens is prohibited at Huntley Meadows Park. Further, a permit for Collection of Wildlife for Scientific and/or Educational Purposes is required anywhere in the Commonwealth of Virginia.

Copyright © 2015 Walter Sanford. All rights reserved.


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