On 30 August 2015, I spotted a large, mutant damselfly at Huntley Meadows Park. Kidding! It’s actually a small toy damselfly finger puppet that I bought at the HMP Visitor Center gift shop last year.
The Raynox DCR-250 close-up filter is a relatively inexpensive solution that enables my Panasonic superzoom digital camera to be used for macro photography. Set-up is quick and easy — the filter simply clips on the front of the camera lens using a universal adapter, just like a lens cap. I use a 52mm-to-43mm step-down ring to mount the Raynox close-up filter more securely. (See “Editor’s Note” at the end of this post.)
Since depth-of-field is very shallow with a close-up filter, I used Adobe Photoshop CC 2015 to create the following composite image in which the entire subject appears in focus.
The Raynox DCR-250, like other close-up filters and extension tubes, reduces the minimum focusing distance between the lens and subject. Each focus layer was taken using 6/24x zoom telephoto at an estimated working distance of six-to-10 inches (~6-10″) from the subject. It’s worth noting the in-camera manual focus digital distance scale incorrectly showed the working distance was between three and six feet!
The composite image isn’t perfect. For example, the nose seems to be slightly out-of-focus in Focus Layer 1. Also notice there is some “flaring” (for lack of a better term) on the sides of the thorax shown in both Focus Layer 1 and 13 that was retained in the final version. Overall, not bad for a first effort.
Imagine how cool it would be to create a focus stacked image of a real odonate! Easier said than done. I’m exploring several solutions, one of which seems do-able in the field. In the meantime, experience gained from my “studio” experimentation should help when it’s time to photograph several odonate evuviae I have collected.
This post features photos of two Widow Skimmer dragonflies that appear virtually identical: one is a female; the other is an immature male. The simplest way to tell the difference between the two dragonflies is by looking at their terminal appendages.
The first photo shows a female Widow Skimmer dragonfly perching alongside Plantation Drive in the community of Woodlawn Village (near Jackson Miles Abbott Wetland Refuge), Fairfax County, Virginia USA.
24 JUL 2015 | Woodlawn Village | Widow Skimmer (female)
The last photo shows an immature male Widow Skimmer perching in a small meadow near a vernal pool at Huntley Meadows Park (HMP).
Who knew toads are more popular than dragonflies? I didn’t. That is, until YouTube sent a notification that one of my toad videos had reached 1,000 views during the first week in June 2015. 1,561 views as of this writing. Not exactly “going viral,” but hey, not bad for an amateur movie maker like me.
C’mon, let’s be honest — toads are really ugly! I’m guessing “beautiful” is not the first word you think of when looking at the Eastern American Toad (Anaxyrus americanus) featured in this post. Good “camouflage” is the first word I thought of, so good that I didn’t see the toad until it moved when I almost stepped on it.
On the other hand, dragonflies are beautiful. Makes me wonder why toads are more popular than dragonflies, that is, as measured by YouTube views. I have two theories.
Theory No. 2 seems more plausible: I’m guessing one or more educators, including classroom teachers and/or science resource teachers, featured my video as part of a lesson/unit on amphibians. I wonder whether it’s possible to see how many views originated from the “.edu” Internet domain.
It is uncommon to see the broad-winged skimmers from the genus Tramea perching. Dragonflies are classified as either “fliers” or “perchers,” based upon their feeding habits. Black Saddlebags are fliers.
Black Saddlebags is one of at least five major species of dragonflies known to be migratory in North America. Broad hindwings is an adaptation that enables Black Saddlebags to glide easily when flying. Dragonflies expend less energy when gliding, an aide to long-distance migration. According to the axiom in biology/morphology, form follows function.
Slaty Skimmer dragonflies (Libellula incesta), such as the mature male shown below, look somewhat similar to Black Saddlebags. Slaty Skimmers are “perchers.” Slaty Skimmers aren’t migratory; notice their hindwings are narrower than Black Saddlebags.
The bioswale was designed to filter the runoff which comes from the parking lot, removing heavy metals, salt, sand, etc. from the runoff before conveyance to Dogue Creek. It is supposed to slowly filter the rain water in 48-72 hours, to clean and purify the water before entering the creek. Source Credit: David M. Lawlor, Natural Resource Manager, HMP.
Did you notice the odonate exuvia located on the same reed as the Common Green Darners? Although it’s usually impossible to identify an exuvia from a photograph like the one shown above, I consulted the experts of the Northeast Odonata Facebook group.
I can’t identify the exuvia to species, but I’m pretty confident about the family — Libellulidae, a skimmer. Possibly Blue Dasher, but I’m mostly guessing there. Source Credit: Christopher E. Hill, Associate Professor, Department of Biology, Coastal Carolina University.
Eggs may hatch after a few days, or embryonic development may take a month or more. In some species, the eggs overwinter and hatch the following spring. Each egg hatches into a very tiny prolarva that looks like a primitive insect form, quite different from the larva that will succeed it. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Locations 407-409). Princeton University Press. Kindle Edition.
As odonate larvae grow and outgrow their skin, they molt, on average 12 times. The duration of this stage of life can vary from a month to several years, depending upon both species and climate. The last molt, called “emergence,” is the metamorphosis from larva to adult; the “cast skin” that is left behind is an exuvia (pl. exuviae).
The juxtaposition of the exuvia and mating pair in the first photo is a metaphor for the circle of life, come full circle: eggs; prolarvae; larvae; emergence/adult males and females; mating pairs; males guide females to egg-laying sites.
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.
The following annotated image illustrates some of the reproductive anatomy of male and female Southern Spreadwing damselflies.
08 MAY 2015 | HMP | Southern Spreadwing (mating pair, in tandem)
The following annotated image illustrates some of the reproductive anatomy of a female Southern Spreadwing: two cerci (sing. cercus), superior appendages that have little or no function; two styli (sing. stylus), structures that serve as sensors in egg positioning; and an ovipositor (shown above) that is used to insert eggs into vegetation (endophytic oviposition).
According to Ed Lam, author and illustrator of Damselflies of the Northeast, “male Southern and Sweetflag cannot be separated in the field.” It is possible to reverse-engineer a positive identification based upon a single key field mark for female specimens of the two species: Southern Spreadwing females have a much smaller ovipositor than Sweetflag Spreadwing females, as illustrated in the following references.
Odes for Beginners | Damselfly Claspers & Genitalia | Note the differences in the ovipositors between Common (top) and Sweetflag Spreadwings. Editor’s Note: Common Spreadwing has been split into two species: Northern Spreadwing; and Southern Spreadwing.
After a male damselfly grabs a female with his claspers, he transfers sperm from the genital opening under the ninth abdominal segment (S9) to his hamules, shown above, located beneath the second abdominal segment (S2). Next the pair forms the mating wheel, then the male transfers sperm from his hamules to the female through her genital pore under the eighth abdominal segment (S8). The beginning-to-end process is shown in the following still photos and two-part series of videos.
Family Coenagrionidae (Narrow-winged Damselflies) is comprised of 14 genera. Three genera are common in Northern Virginia: Argia (Dancers); Enallagma (American Bluets); and Ischnura (Forktails).
Several species of Argia are relatively common in Northern Virginia parks: Blue-tipped Dancer and Variable Dancer are featured in this post; Blue-fronted Dancer was featured in a recent blog post.
It’s helpful to get shots of mating pairs 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 Argia (Dancers) fit into the bigger picture of the Order Odonata, Suborder Zygoptera (Damselflies).
There are four 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 Coenagrionidae is comprised of 14 genera. Three genera are common in Northern Virginia: Argia (Dancers); Enallagma (American Bluets); and Ischnura (Forktails).
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!
Editor’s Note: Please comment to let me know whether the preceding information is helpful.
walter sanford's photoblog 