Archive for May, 2017
May 30, 2017
A Swift River Cruiser dragonfly (Macromia illinoiensis) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a late-stage emergent teneral female, as indicated by her terminal appendages.
Many of the major milestones during the miraculous process of emergence occurred before I spotted the dragonfly. I photographed the process from the first sighting to the time when I had to stop (see The Backstory, below): I shot 102 photos in approximately one hour; time is compressed by showcasing five (5) select photos from the first-to-last sighting.
The following photo is the first image from a time-series documenting the late-stage emergence of the teneral female. Elapsed time is expressed in hh:mm:ss format, e.g., 00:00:00 is the time when I spotted the emergent teneral female, and 01:01:15 is the total elapsed time.
27 MAY 2017 | 09:09:13 am EDT | Elapsed time: 00:00:00
The wings seem to be fully expanded (as shown in the preceding photo), evidenced by the fact that it appears some of the greenish hemolymph has been pumped out of the wings and into the abdomen.
27 MAY 2017 | 09:51:08 am EDT | Elapsed time: 00:41:55
Notice the wings are mostly clear in the following photo, in contrast with the first photo in this gallery. Next the abdomen expanded slowly until it was longer than the wings, as shown in the last photo.
27 MAY 2017 | 09:52:33 am EDT | Elapsed time: 00:43:20
As time passed, more of the adult coloration began to appear. Notice the large yellow spot on the dorsal side of abdominal segment seven (S7).
27 MAY 2017 | 09:57:39 am EDT | Elapsed time: 00:48:26
The last photo shows the dragonfly waiting for the wings and body to harden before its first flight.
27 MAY 2017 | 10:10:28 am EDT | Elapsed time: 01:01:15
The Backstory
I woke up at 4:30 a.m. in order to be at Riverbend Park when the gates open at 7 a.m. I had to attend a training session in order to be a volunteer collector of dragonfly exuviae for a research program sponsored by the park. The class started at 10 a.m., but I wanted to look around and shoot photos before the class.
I found almost nothing photo-worthy until soon after 9:00 a.m. when I spotted the emergent Swift River Cruiser dragonfly. The emergence was well underway at that point; I had to go to class before the wings spread and the teneral dragonfly flew away.
The emergence site was in a high-traffic location, so the daughter of a woman in the class guarded/watched the teneral until it flew away safely. After class, I collected the exuvia. I will shoot a set of studio macro photographs of the exuvia before returning the specimen to the park.
Swift River Cruiser is a new species of dragonfly for my life list.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:emergence, Family Macromiidae (Cruisers), female, hemolymph, Macromia illinoiensis, Potomac River, Riverbend Park, Swift River Cruiser dragonfly, teneral
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, education, natural science, Panasonic DMC-FZ150, wildlife photography | 16 Comments »
May 28, 2017
I liked to make paper- and plastic models when I was a child. Seems like the directions for assembling many models — not that anyone reads the directions — always started by saying something like “Insert Tab A in Slot B.”
Oddly enough, that line reminds me of how odonates copulate, in general, and Cobra Clubtail dragonflies (Gomphurus vastus) in particular.
Male
The hamules are “Tab A.”
Female
The subgenital plate is “Slot B.”
Putting it all together
Insert Tab A in Slot B. That’s the PG-rated version of how Cobra Clubtail dragonflies copulate in order to reproduce.
The Backstory
There is an annual mass emergence of Cobra Clubtails during the first week-or-two of May at Riverbend Park. It’s a spectacular event worth seeing firsthand!
The following photo shows a dead female, one of several Cobra Clubtails that were trampled by groups of elementary school children visiting the park on 09 May 2017. Her premature death saddens me because it was avoidable — the students should have been warned to watch their step because there were lots of Cobra Clubtails perching on the ground almost everywhere.
In the hope the female didn’t die in vein, I reluctantly decided to photograph the corpse in order to illustrate her external reproductive anatomy.
Editor’s Note: Sincere thanks to Dennis Paulson for help in identifying the female parts on the ventral side of abdominal segments eight and nine (S8-9).
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:Cobra Clubtail dragonfly, female, Gomphurus vastus, hamules, male, Potomac River, Riverbend Park, subgenital plate
Posted in Aperture, digital photography, dragonflies, education, Fujifilm EF-X500, Fujifilm X-T1, natural science, Photoshop, wildlife photography | Leave a Comment »
May 26, 2017
A crayfish was spotted in the shallows of Bull Run, under several inches of water. I estimate it was 3-4 in (~7.6-10.2 cm) in length.
Many crayfish can be particularly hard to identify from a photograph and many new species are still being discovered in Virginia’s waterways. This large crayfish is from the Family Cambaridae and is likely a native species. Other crayfish found in Northern Virginia, like the rusty crayfish (Orconectes rusticus) and red swamp crayfish (Procambarus clarkii), were likely introduced via the food industry and pose a serious threat to native crayfish populations. Source Credit: John Burke, Ecologist III, Stormwater Management Branch, Fairfax County Department of Public Works and Environmental Services.
10 MAY 2017 | Fairfax County, VA | crayfish (underwater)
Notice the first, second, and third pairs of walking legs feature chelae (plural).
A chela /kˈiːlə/, also named claw, nipper, or pincer, is a pincer-like organ terminating certain limbs of some arthropods. The name comes from Greek (χηλή) through New Latin (chela). The plural form is chelae. Legs bearing a chela are called chelipeds. Source Credit: Chela (organ), Wikipedia.
Also notice the slimy stuff on the rocks that makes them super slippery!
The slimy, slippery coating you find on rocks in aquatic systems is periphyton. In freshwater systems, periphyton is mostly comprised of algae but other microorganisms and detritus also collect on submerged rocks. Periphyton serves as an essential food source to many aquatic organisms and can also act as a bioindicator, signaling changes in water chemistry and nutrient levels in the system (Chetelat et al. 1997). Source Credit: John Burke.
Tech Tip: My Canon 580EX Speedlite external flash unit was set for 1/16 power in order to penetrate the water and illuminate the subject on a bright, sunny day.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:crayfish, Fairfax County, Family Cambaridae, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, education, How To, natural science, Panasonic DMC-FZ150, wildlife photography | 1 Comment »
May 24, 2017
The only downside — or upside, depending upon your point of view — to my new hotspot for hunting odonates is there are only two trails in/out and both paths are steeply-inclined. Going in, not so bad walking downhill; going out, not so much fun!
I stopped to catch my breath as I was walking up a long trail with a 45-degree slope. I heard a rustling sound in the vegetation on the left side of the trail, a little beyond where I was standing. I moved closer slowly until I spotted my first Eastern Hog-nosed Snake (Heterodon platirhinos)!
Although the name for this snake is less than flattering, notice the distinctive orange fleur-de-lis shape on top of its head. The coloration of Eastern Hog-nosed Snake is variable; I was fortunate to see one of the more colorful ones.
I never had a clear view of the entire snake, but I estimate it was two-to-three feet in length.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:Eastern Hog-nosed Snake, Fairfax County, Heterodon platirhinos, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, natural science, Panasonic DMC-FZ150, photowalking, reptiles, wildlife photography | 4 Comments »
May 22, 2017
Several Eastern Pondhawk dragonflies (Erythemis simplicicollis) were spotted during a photowalk along a mid-size stream in Fairfax County, Virginia USA.
For some types of dragonflies, immature males have the same coloration as females of the same species. This is true for many members of the Family Libellulidae (Skimmers) such as Eastern Pondhawk. Terminal appendages can be used to identify gender.
The Backstory
I visited a new location in Fairfax County, Virginia on 03 May 2017, following my hunch that the spot might be a good place to find some of the more uncommon species of odonates. Turns out my hunch was right!
I revisited the same location a week later. Let’s just say lightning didn’t strike the same place twice. I saw several Eastern Pondhawks but none of the uncommon species of odonates that I saw a week earlier. I don’t know whether it’s phenology or the fact that Eastern Pondhawks are voracious predators, but it seems like whenever they show up it’s game over for the uncommon species of dragonflies and damselflies that emerge during spring. By the way, that explains the title of this post.
When I see the first-of-season Eastern Pondhawks, I start singing “The Party’s Over” like Don Meredith used to at the end of Monday Night Football games on ABC-TV. Yes, I’m old enough to remember Dandy Don!
Related Resources:
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:Eastern Pondhawk dragonfly, Erythemis simplicicollis, Fairfax County, Family Libellulidae (Skimmers), female, immature male, phenology, terminal appendages, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, natural science, Panasonic DMC-FZ150, photowalking, wildlife photography | Leave a Comment »
May 20, 2017
An Ashy Clubtail (Phanogomphus lividus) was spotted during a photowalk along a mid-size stream in Fairfax County, Virginia USA.
This individual is a male, as indicated by his terminal appendages and indented hind wings.
The last photo is uncropped. The wider view shows the Ashy Clubtail is well-camouflaged when perching on the ground.
The Backstory
I visited a new location in Fairfax County, Virginia on 03 May 2017, following my hunch that the spot might be a good place to find some of the more uncommon species of odonates. Turns out my hunch was right!
I saw species from four families of dragonflies: male Stream Cruiser dragonfly (Didymops transversa); male Springtime Darner dragonfly (Basiaeschna janata); female and male Common Baskettail dragonfly (Epitheca cynosura); female and male Spine-crowned Clubtail dragonfly (Hylogomphus abbreviatus); at least two male Lancet Clubtail dragonflies (Phanogomphus exilis); and the male Ashy Clubtail (Phanogomphus lividus) featured in this post.
In addition, I saw lots of teneral damselflies from the Family Coenagrionidae (Pond Damsels), possibly Blue-tipped Dancer (Argia tibialis).
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:03MAY2017, Ashy Clubtail dragonfly, Fairfax County, Family Aeshnidae (Darners), Family Coenagrionidae, Family Corduliidae (Emeralds), Family Gomphidae (Clubtails), Family Macromiidae (Cruisers), female, male, Phanogomphus lividus, Pond Damsels Family, terminal appendages, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, natural science, Panasonic DMC-FZ150, photowalking, wildlife photography | Leave a Comment »
May 18, 2017
A male and female Common Baskettail dragonfly (Epitheca cynosura) were spotted recently at the same location in Fairfax County, Virginia USA.
Male and female Common Baskettails look similar. Terminal appendages can be used to identify gender.
Male
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”).
(See a full-size version of the original photo, without annotation.)
Female
Female dragonflies have a pair of cerci (superior appendages) that have little or no function. The abdomen of female Common Baskettails is noticeably thicker than males of the same species.
(See a full-size version of the original photo, without annotation.)
A better view of the subgenital plate is provided by the following digital scan of the underside of the abdomen of a female Common Baskettail. The subgenital plate looks a little like a pair of calipers. Also known as vulvar lamina, the subgenital plate is located under the ninth abdominal segment (S9) of some female odonates and “serves to hold eggs in place during exophytic oviposition.” Remember that all dragonflies and damselflies have a 10-segmented abdomen, numbered from front to back.
Image used with permission from Ed Lam.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:03MAY2017, cerci, claspers, Common Baskettail dragonfly, epiproct, Epitheca cynosura, Fairfax County, male, subgenital plate, terminal appendages, Virginia, vulvar lamina
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, education, natural science, Panasonic DMC-FZ150, Photoshop, wildlife photography | 2 Comments »
May 16, 2017
Why do I hunt odonates, that is, dragonflies and damselflies? I like being outdoors, visiting beautiful natural places. I like honing my skills as a wildlife photographer. Most importantly, it’s fun! I like the challenge of finding uncommon species, and the thrill of making new discoveries.
A Cobra Clubtail dragonfly (Gomphurus vastus) was spotted along the Potomac River at Riverbend Park, Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and indented hind wings.
The male was perching on colorful kayaks stored in a wooden rack near the boat ramp. Notice the natural coloration of the dragonfly was affected by light reflected from the kayaks. That’s OK since this photo set is all about fun, right?
Can you say “hamules?” Males of many species in the Family Gomphidae (Clubtails) have prominent secondary sex organs.
Tech Tips: I carried two digital cameras during the trip to Riverbend Park: a Panasonic Lumix DMC-FZ150 superzoom bridge camera plus Canon 580EX Speedlite, my go-to kit for photowalking; as well as my Fujifilm X-T1, Fujinon XF55-200mm zoom lens, and Fujifilm EF-X500 shoe mount flash. Since Fujifilm digital cameras are well-known for capturing vivid color, the X-T1 was the camera of choice for this colorful scene.
Editor’s Note: 16 May is the one-year anniversary of my first visit to Riverbend Park to see the annual mass emergence of Cobra Clubtail dragonflies that occurs during the first two weeks in May.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:Cobra Clubtail dragonfly, Family Gomphidae (Clubtails), Gomphurus vastus, hamules, male, Potomac River, Riverbend Park, terminal appendages
Posted in Aperture, digital photography, dragonflies, Fujifilm EF-X500, Fujifilm X-T1, natural science, wildlife photography | 2 Comments »
May 14, 2017
At least two Lancet Clubtail dragonflies (Phanogomphus exilis) were spotted during a photowalk along a mid-size stream in Fairfax County, Virginia USA.
These individuals are males, as indicated by their terminal appendages and indented hind wings.
The next photograph was taken at a later time than the first two photos. All of the photos in this post were taken near the same location. Is this another male, or the same one featured in the preceding photos? Who knows?
Lancet Clubtail versus Ashy Clubtail
Lancet Clubtail looks similar to Ashy Clubtail (Phanogomphus lividus). The only way to differentiate the two species with certainty is to examine their external reproductive anatomy; this is impossible unless the specimens are captured and examined in-hand.
Relative size is used sometimes to identify the two species: Lancet Clubtail is slightly smaller than Ashy Clubtail. There are two problems with this method of identification. First, it is virtually impossible to determine the exact size of a specimen in the field unless it is captured and measured. Second, some natural variation in size should be expected among individuals of the same species.
A quick-and-dirty method for differentiating Lancet- and Ashy Clubtails with some degree of certainty is to look at the markings on abdominal segments eight and nine (S8-9). Lancet Clubtail has a “spearpoint” on top of abdominal segment eight (S8) that almost reaches the end of the segment, a wide yellow stripe on top of segment nine (S9), and irregular yellow markings on the sides of segments eight and nine (S8-9).
(See a full-size version of the original photo, without annotation and inset photo of Ashy Clubtail.)
In contrast, Ashy Clubtail has a spearpoint on top of abdominal segment eight (S8) that is less than half the length of the segment, segment nine (S9) may or may not have a pale yellow stripe on top, and the sides of segments eight and nine (S8-9) may or may not have “poorly defined” yellow markings.
(See a full-size version of the original photo, without annotation.)
Coloration is variable among individuals of the same species, so looking at abdominal markings isn’t always a reliable method of identification. In this case, it works beautifully.
Editor’s Note: The word “spearpoint” and the phrase “poorly defined” are descriptors attributed to Dennis Paulson, Dragonflies and Damselflies of the East (Princeton Field Guides). Princeton University Press. Kindle Edition.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:03MAY2017, Ashy Clubtail dragonfly, Fairfax County, Family Gomphidae (Clubtails), Lancet Clubtail dragonfly, male, Phanogomphus exilis, Phanogomphus lividus, terminal appendages, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, education, natural science, Panasonic DMC-FZ150, Photoshop, photowalking, wildlife photography | 1 Comment »
May 12, 2017
A Stream Cruiser dragonfly (Didymops transversa) was spotted during a photowalk along a mid-size stream in Fairfax County, Virginia USA. This individual is a male, as indicated by his terminal appendages and indented hind wings.
Male: Eyes brown with green highlight above. … Female: Eyes brown. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 7192, 7194-7195). Princeton University Press. Kindle Edition.
I’ve never seen a green-eyed Stream Cruiser like this one — every one had brown eyes, including both males and females.
Copyright © 2017 Walter Sanford. All rights reserved.
Tags:03MAY2017, Didymops transversa, Fairfax County, Family Macromiidae (Cruisers), male, Stream Cruiser dragonfly, terminal appendages, Virginia
Posted in Aperture, Canon 580EX Speedlite, digital photography, dragonflies, natural science, Panasonic DMC-FZ150, photowalking, wildlife photography | Leave a Comment »
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