Archive for April, 2019

Painted Skimmer dragonfly (female)

April 29, 2019

Painted Skimmer (Libellula semifasciata) is one of my favorite species in the Family Libellulidae (Skimmers). It’s hard to believe I didn’t post any photos of this beautiful dragonfly during 2018!

This individual is a female, as indicated by her terminal appendages. She was spotted near a mid-sized pond at the North Tract of Patuxent Research Refuge, Laurel, Maryland USA.

Copyright © 2019 Walter Sanford. All rights reserved.

Advertisements

Beware of dismissive thinking!

April 26, 2019

An unknown species of teneral baskettail dragonfly (Epitheca sp.), possibly either Common Baskettail (E. cynosura) or Robust Baskettail (E. spinosa), was spotted near a mid-sized pond at the North Tract of Patuxent Research Refuge, Laurel, Maryland USA.

This individual is a female, as indicated by its terminal appendages.

That’s a very wide abdomen, hairy thorax, and cerci as long (if not slightly longer) as S9. I’m fairly confident it’s a Robust Baskettail but I have limited experience with that species. The pattern of dark spots at the wing base is definitive for Robust but I can’t see them well in your picture. Mike Moore’s opinion would he good. Source Credit: Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group.

I consulted Dr. Michael Moore.

It certainly suggests Robust based on the dimensions of the abdomen and the “hairiness” of the thorax but I would really need to see the pattern of black at the base of the hind wings to be sure. Female Commons can be surprisingly fat. Source Credit: Dr. Michael Moore, a professor in the Department of Biological Sciences at University of Delaware and odonate expert extraordinaire. Dr. Moore’s new Web site is a treasure trove of helpful resources.

The reason neither Mike nor Michael can see the definitive field mark on the base of the baskettail dragonfly’s hind wings is because this individual is a late-stage emergent teneral and its wings haven’t opened.

Regardless of the species of dragonfly, emergence is an essentially identical process. See “Related Resources” (below) for a time-series of photographs showing part of the process of emergence for a female Common Baskettail.

The danger of dismissive thinking.

This sighting was another reminder of one of many “Walterisms”: “Don’t be dismissive!” Huh?

During a recent trip to the Patuxent Research Refuge in search of Harlequin Darner (G. furcillata), my good friend Mike Powell and I saw many basktettails, mostly Common Baskettail. Common. That’s the key word. When I noticed several baskettails, I thought, “Oh, Common Baskettails. Nothing to see here, folks. Move along. Must find Harlequin!”

As it turns out, my laser-like focus on finding my first Harlequin Darner might have caused me to miss an opportunity to see a Robust Baskettail — another new species for my life list of odonates. Once again I’m reminded that dismissive thinking can be wrong-headed.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Harlequin Darner dragonfly (female)

April 24, 2019

On Earth Day 2019 my good friend Mike Powell and I traveled to the North Tract of Patuxent Research Refuge, Laurel, Maryland USA. Our target species: Harlequin Darner (Gomphaeschna furcillata), one of only two species in Genus Gomphaeschna, the Pygmy Darners.

Working the shot

A Harlequin Darner dragonfly was perched on a tree, approximately head height, near a mid-sized pond. This individual is a female, as indicated by her rounded hind wings and terminal appendages. All female dragonflies have a pair of cerci (superior appendages) that have little or no function. Both cerci are visible clearly in the full-sized version of the following photo.

Harlequin Darner is a new species for my life list of odonates.

First contact

Those who know me well are familiar with one of many “Walterisms”: “Get a shot, any shot; refine the shot.” The following photo is the “record shot”; the preceding photo shows one of my attempts to refine the record shot.

The record shot shows a better view of the female’s face than the refined shot, as shown in the following closer crop of the same photo.

Credits

Sincere thanks to Richard Orr and Rick Borchelt for detailed guidance regarding two sites where Harlequin Darner is known to occur at Patuxent Research Refuge as well as lots of practical tips for finding G. furcillata in the field.

Richard is a renowned expert on odonates of the mid-Atlantic region of the United States, and Rick is Director for Communications and Public Affairs, Office of Science at U.S. Department of Energy.

The Backstory

Harlequin Darner and Taper-tailed Darner (Gomphaeschna antilope) are sibling species. Taper-tailed Darner is known to occur at Huntley Meadows Park, based upon confirmed sightings by Geoffrey Cohrs and Karen Sheffield, park staff members, Fred Siskind, park volunteer (photo used with permission), and Daryl & Erin Elliott. Since both Harlequin and Taper-tailed Darner are in the same genus and prefer the same habit, I speculated Harlequin should be found at Huntley Meadows too. Every spring I wandered the wetlands of Huntley Meadows Park in search of both species of the elusive Pygmy Darners. No luck.

After three years of frustration, I decided to expand my search area to include two hotspots in Maryland where there is a better chance of finding Harlequin Darner. I was fortunate to find my first Harlequin at the location closer to my home in Northern Virginia.

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

  • Genus Gomphaeschna | G. furcillata | Harlequin Darner | male | top view
  • Genus Gomphaeschna | G. furcillata | Harlequin Darner | male | side view

See also Harlequin Darner dragonfly for Mike Powell’s take on our trip to Patuxent Research Refuge.

Copyright © 2019 Walter Sanford. All rights reserved.

Battery Economics 101

April 22, 2019

I bought a package of eight (8) Energizer Ultimate Lithium AA batteries for $13.28 at Loew’s (hardware store) recently. Assuming that’s a typical price point — and it may not be since retail stores are well known for inflating the price of “impulse buy” items placed near the checkout stands — I wondered which type of battery is the better value, primary cells (like the Energizers) or secondary cells (i.e., rechargeable batteries)?

B&H Photo sells an 8-Pack of Panasonic eneloop pro AA Rechargeable NiMH Batteries (1.2V, 2550mAh) for $32.99.

At face value, rechargeable batteries cost ~2.5x more than primary cells. But the secondary cells are rechargeable up to 500 times! In other words, the consumer will recover the extra cost of secondary cells after recharging them only a few times.

External flash units can be real Energy Hogs, especially when shooting at higher flash ratios. So a word to the wise consumer, get a set of rechargeable batteries — they’re worth the extra cost.

Post Addendum

My good friend Mike Powell suggested this blog post should be updated to mention that rechargeable batteries require a charger. I recommend the following combo deal available from B&H Photo: Panasonic Eneloop Pro Rechargeable AA Ni-MH Batteries with Charger (2550mAh, Pack of Four) that sells for $26.30. Done!

Copyright © 2019 Walter Sanford. All rights reserved.

Uhler’s Sundragon (female)

April 19, 2019

A Uhler’s Sundragon (Helocordulia uhleri) was spotted during a photowalk along a mid-size stream at an undisclosed location in Northern Virginia USA.

This individual is a female, as indicated by her rounded hind wings and terminal appendages. All female dragonflies have a pair of cerci (superior appendages) that have little or no function. Both cerci are visible clearly in the full-size version of the following photo.

16 APR 2019 | Northern Virginia | Uhler’s Sundragon (female)

Notice the right hind wing is slightly malformed. It appears the wing failed to inflate completely during emergence. The malformation didn’t impair her ability to fly. Pollen (probably tree pollen) is especially noticeable on the darker parts of the body.

Just the facts, ma’am.

According to records for the Commonwealth of Virginia maintained by Dr. Steve Roble, Staff Zoologist at the Virginia Department of Conservation and Recreation, Division of Natural Heritage, the adult flight period for H. uhleri is 29 March to 27 June. The species is classified as common. Its habitat is “streams.”

Bear in mind, Dr. Roble’s records are for the entire state, therefore the adult flight period for H. uhleri seems to be longer than it is in reality. The adult flight period for a single site is probably no more than a month, and more likely around two-to-three weeks. For example, according to records for Northern Virginia maintained by Kevin Munroe, former manager of Huntley Meadows Park, the adult flight period for Uhler’s is 11 April to 05 May.

It’s also worth noting that the window of opportunity to see Uhler’s Sundragon closes rapidly after trees are in full leaf.

Is Uhler’s Sundragon common? I guess the answer to that question depends upon where you live. In Northern Virginia, Kevin Munroe classified H. uhleri as “rare.” In fact, I’m aware of only one location in Northern Virginia where Uhler’s Sundragon can be found with reasonable certainty.

Copyright © 2019 Walter Sanford. All rights reserved.

Uhler’s Sundragon (male)

April 17, 2019

A Uhler’s Sundragon (Helocordulia uhleri) was spotted during a photowalk along a mid-size stream at an undisclosed location in Northern Virginia USA. Uhler’s Sundragon is a new species for my life list of odonates.

16 APR 2019 | Northern Virginia | Uhler’s Sundragon (male)

This individual is a male, as indicated by its “indented” hind wings and terminal appendages.

Off-season Homework Pays Dividends

Planning for the next season is a good way to stay connected with odonates during the winter months. One off-season activity that can pay big dividends in the future is to research sites for finding new life-list species of dragonflies and damselflies, especially rare and uncommon species.

Uhler’s is No. 1 on my list of target species for 2019. During the winter of 2018-2019, I researched potential sites for finding Uhler’s Sundragon. I’m pleased to report “Mission accomplished!”

Credits

I’ve been dogged by, er, let’s just say “transportation issues” for months. Sincere thanks to my buddy Mike Powell for scouting one of the sites I researched and guiding me to a couple spots where he found Uhler’s. Good work, Mike — couldn’t have done it without you!

Also thanks to Michael Boatwright, founder and administrator of the Virginia Odonata Facebook group, for providing lots of practical tips for finding Uhler’s Sundragon in the field.

Related Resources

Copyright © 2019 Walter Sanford. All rights reserved.

Left on the cutting room floor

April 15, 2019

Close readers of my blog may have noticed I’ve posted a lot of photos recently that were taken years ago. Why were the photos passed over for publication closer to the time the shots were taken?

Sometimes there are better shots from the same photowalk that I’m eager to share, and sometimes they just don’t make the grade. The former requires no explanation; the following photos help to illustrate the latter.

The following female Slender Spreadwing damselfly (Lestes rectangularis) was spotted during a photowalk around a vernal pool in the forest at Huntley Meadows Park. The damselfly was perched in a hidey-hole in the vegetation at angle that made it impossible to get the entire subject in focus from head-to-tail.

The first photo shows the head and thorax in focus, but the tip of the abdomen and terminal appendages are out of focus.

15 SEP 2016 | HMP | Slender Spreadwing (female)

The last photo shows the tip of the abdomen and terminal appendages in focus, but the head and thorax are in soft focus. Look closely at a full-size version of the photo and you can see both styli (sing. stylus), structures that serve as sensors (like “curb feelers“) in egg positioning during oviposition.

15 SEP 2016 | HMP | Slender Spreadwing (female)

The odd thing is the focus point is nearly the same in both photos, and the aperture is identical. Go figure! Anyway, less than ideal focus is something that will cause me to reject photos every time. And then there’s that “too hot” blade of grass in the lower-right corner — talk about distracting!

Copyright © 2019 Walter Sanford. All rights reserved.

Great Blue Skimmer dragonfly (mature male)

April 12, 2019

Great Blue Skimmer dragonfly (Libellula vibrans) was spotted near a vernal pool in the forest at Huntley Meadows Park (HMP), Fairfax County, Virginia USA. This individual is a mature male, as indicated by his terminal appendages, discolored abdomen, and tattered wings.

This male has mated many times, as indicated by the scratches on his abdomen.

Males that have mated often have marks on their abdomen where the female legs have scratched them. This is especially obvious in species in which males develop pruinosity, as the pruinosity on the mid-abdomen is scratched off, and the signs are visible at some distance. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 390-392). Princeton University Press. Kindle Edition.

Copyright © 2019 Walter Sanford. All rights reserved.

So close, yet so far!

April 10, 2019

Two Common Whitetail dragonflies (Plathemis lydia) were spotted perching on a wooden fence rail located near the terminus of the Hike-Bike Trail at Huntley Meadows Park (HMP), Fairfax County, Virginia USA.

The individual shown on the left is a mature female; the one on the right is a mature male.

15 SEP 2016 | HMP | Common Whitetail (mature female and male)

Sexing Common Whitetail dragonflies

For many of the common species of odonates found in Northern Virginia, I created a collection of annotated guides that illustrates how to differentiate gender by looking at terminal appendages. The difference in the pattern of wings spots for male and female Common Whitetails is sufficient to identify gender.

Life Cycle of Odonates

Odonates (dragonflies and damselflies) 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, depending upon the species. 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.

I wonder how these two mature adults were able to be so close yet resist the compelling biological urge to hook up!

Copyright © 2019 Walter Sanford. All rights reserved.

Smeared Dagger Moth caterpillar

April 8, 2019

A Smeared Dagger Moth caterpillar (Acronicta oblinita), a type of stinging caterpillar, was spotted on 15 September 2016 during a photowalk along the boardwalk that goes through the central wetland area at Huntley Meadows Park (HMP).

Stinging caterpillars use poison-filled bristles to defend themselves from predators. If you touch a stinging caterpillar, you’ll know it by the burning, itching… Source Credit: 13 Stinging Caterpillars. [Smeared Dagger is No. 10.]

Thanks to Mike Powell, fellow wildlife photographer and blogger, for identifying this unusual caterpillar way back when both of us were less experienced amateur naturalists.

Copyright © 2019 Walter Sanford. All rights reserved.


%d bloggers like this: