Some dragons of late

A blue dasher, Pachydiplax longipennis, adopts the obelisking posture. On hot days, as this one was, a perched dragonfly will often point its abdomen directly at the sun. By doing so, it minimizes heat absorption by exposing less of its body to direct sunlight. Obelisking dragonflies make for great photographic subjects.

I have been doing my level best this field season to focus on surveying for dragonflies. It's the final year of the three-year Ohio Dragonfly Survey, and our last crack at fleshing out the distribution and status of Ohio's Odonata (damselflies and dragonflies). If you photograph these insects in Ohio, we'd love to have your records and they're very easy to submit. CLICK HERE for instructions.

A Carolina saddlebags, Tramea carolina, moors to an old plant stalk. It's been a good year for these.

I had the good fortune of making a recent foray into various west-central Ohio haunts with uber-dragonflier Jim Lemon. He's submitted over 7,000 records to the Ohio Dragonfly Survey to date, a remarkably prolific effort and far beyond anyone else. This was one of the special species Jim showed me, a jade clubtail, Arigomphus submedianus. Lemon discovered it along the shore of Lake Loramie in Auglaize and Shelby counties last year. It was a new Ohio record, one of a number of state firsts for him.

Jade clubtail's core range is the Great Plains states, well to the west of Ohio. The habitat where Jim found this species is utterly common - shorelines of a large lake, often armored with riprap or with only a fringe of unmowed vegetation. It would seem likely that these showy clubtails inhabit other Ohio lakes, especially in the western part of the state, but no one has yet found others.

As always, click the photo to enlarge

An odd perspective on a slender spreadwing, Lestes rectangularis. This group of damselflies is noted for the wide separation between the eyes, as can clearly be seen here. The animal is perched on the stem of a rush, and was cooperative enough to allow me to sneak into position to make this shot.

Another slender spreadwing, this one carrying a complement of water mites. Such parasitism is very common in damselflies, with the larval mites appearing as tiny reddish-orange bumps on the abdomen, usually towards the base. Apparently newly hatched mites first invade the aquatic larvae of damselflies, and when a larva leaves the water and emerges from its larval case, the mites jump to the teneral (newly emergent) damselfly. Later, when the damselfly enters or nears water to mate or lay eggs, the mites hop into the water where they live out the rest of their life cycle. While the larval water mites do siphon body fluids from the damselfly host via feeding tubes, I don't believe they normally do much harm to the host.

A sphagnum sprite, Nehalennia gracilis, one of our smallest (the smallest?) damsels. They're less than an inch long, and very easily overlooked. Jim also showed me a population of these enchanting little bugs, at a beautiful fen. Sure enough, the small zone supporting these sprites was rich in sphagnum moss. Perhaps the sprites oviposit into the sphagnum and the nymphs then inhabit it, but I'm not sure about this.

Finally, a very common species, and one of our largest and showiest, the twelve-spotted skimmer, Libellula pulchella (pulchella means, essentially, beautiful or pretty). One perk of participating in this survey is the numerous opportunities to photograph these gorgeous insects. Not only that, but highly predacious dragonflies are fascinating to observe. Their powers of flight are often astonishing, and the pursuit of "dragonflying" reminds me of birding in many ways.

Again, for more information about the Ohio Dragonfly Survey, GO HERE.

Orange Bluet, with water mites

A tiny orange bluet, Enallagma signatum, peers at your narrator from its resting spot on a lily pad. There are lots of these handsome insects at my local patch wetland, but one must get there towards day's end to see them. For some reason, the orange/yellow-colored damselflies seem to be largely crepuscular, or active towards evening. I saw plenty of orange bluets on the evening that I made these images; a visit at midday generally produces none. If anyone has an explanation for the dusk-active behavior of this species and its orange ilk, I'd love to hear it.

A male orange bluet shares space on this fragrant water-lily leaf with the exuviae, or shed exoskeleton, of a damselfly larva. I'm guessing the shed is from an orange bluet nymph. The predatory nymphs, or larval stage, of damselflies and dragonflies live a completely aquatic existence. Depending on the species, they may remain under the water as a nymph for anywhere from a few months to several years in the case of certain large dragonflies. When the fateful evening arrives, the nymph crawls from the water and clambers onto a plant or some other structure, and undergoes a remarkable transformation to the winged adult. I once was fortunate to stumble into a wandering glider bursting from its exuviae, and photo-documented the process HERE.

A male orange bluet is truly tiny, measuring not much more than an inch from stem to stern. Luckily they are much "tamer" than most larger dragonflies, and by slowly wading up to their lily pad perches, I am able to get my lens pretty close. Still, their minuscule size taxes the limits of my Nikon's 105 mm macro lens, and handholding the rig and making clear crisp shots is a challenge.

As I scoped the animal through my lens, I noticed it carried some baggage. Those little globules on the underside of the bluet's thorax are water mites, in the genus Arrenurus (presumably). These mites are parasitic on damselflies, and can occur on their hosts commonly. Studies of water mite/damselfly infestations have found anywhere from 10% to over 50% of a given damselfly population can be parasitized by mites. The mites are not benign; their purposes for attaching to a damselfly are twofold. One, the mite taps directly into its host and extracts bodily fluids, and the greater the number of mites that are present, the greater the reduction in fitness of the damselfly. Two, the damselflies essentially serve as winged taxi cabs, hauling the water mites to new areas that can be colonized. Flighted insects, and birds, play an enormous role in the dispersal of other organisms, whether they want to or not.