The Intricacies of Dragonfly Flight

Photographing dragonflies is an alluring pursuit both because of their physical beauty and because of their mysterious, unmatched abilities on the wing. The difficulty of getting good pictures is part of the allure. For a still portrait you have to locate the subject and get close without startling it. Useful images of a dragonfly's aerial movements are even more elusive.

Spot-winged Glider

The defining spots for this species' name are scarcely visible when it is at rest. They are located at the rear of the hind wings, alongside the abdomen. In this photograph they seem only slight smudges on the reticulations of the wing membrane.

The flight picture above better shows the nominative spots, while suggesting the difficulty of obtaining a clear aerial image.

However, there was ample evidence in this series of stop-action photos to convince me that there is more to dragonfly flight than vigorous flapping of the wings.

The pictures show wings in various postures, angles, and sequences. I had to know more about this.

I found on line this eye-opening video study (viewer friendly but sophisticated = well-funded) of masterful physiology, The Insane Biology of: The Dragonfly. Printed below are excerpts from the transcript worth reading for a deeper appreciation of one of nature's marvels. Its mechanics are being closely studied by aeronautical engineers and assimilated into drone prototypes.

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Few other insects use direct flight muscles. Most winged insects have what are known as indirect flight muscles, which attach to the walls of the thorax, making the thorax deform as they expand and contract. The deformation of the thorax transmits its resonance to the wings, making them vibrate and initiate the flapping motion. While indirect flight muscles have their own advantages, dragonflies instead have individual muscles that attach directly to the base of each of their four wings. Being able to turn on each wing individually enables them to move and direct each of their four wings independently, in all three axes, meaning they can control their horizontal, vertical, and torsional motions, granting them precision and agility that is unparalleled by most insects with indirect flight muscles. Thanks to these independent controls, dragonflies are one of the few insects that can propel themselves in all six directions: left, right, up, down, forward, and even backward.

Another remarkable way that dragonfly flight differs from other insects is their ability to flap their fore and hind wings in different phases, and can vary that phase depending on maneuvers they wish to perform. One flight technique is known as counter-stroking, where they flap their fore and hind wings one hundred and eighty degrees out of phase with each other. This allows them to hover or engage in very slow forward flight, and can generate large amounts of lift.

For fast forward flight, they are able to switch to phased stroking, where the hind wings beat ninety degrees ahead in phase of the forewings. While this generates far less lift, it generates a lot more thrust, with some species being capable of reaching well over fifty kilometers an hour, making them by far the fastest flying insects.

Dragonflies can also engage in synchronized stroking, which is when the fore wings and hind wings flap together at the same time. This is most useful to increase their acceleration, and to prepare for turning or changing directions quickly. It allows them to generate huge amounts of lift, but can't be sustained for long periods of time, so they generally only use this configuration when chasing prey.

In addition, dragonflies are also capable of flying backwards, a flight maneuver that is not possible for almost any other animal, except a few other small types of flies and the hummingbird. They do this by tilting their bodies upward at ninety degrees, to change the direction of the force generated by the wings.

Finally, dragonflies can also choose to not flap their wings at all, allowing them to free glide, take advantage of an updraft, or, in the case of some female dragonflies, take a ride with a male who can hold onto her, making him beat his wings to propel the two of them.

Dragonfly Dramas

 

Common Green Darner

A hefty dragonfly called the Common Green Darner makes its home around the Halibut Point ponds, those small quarrying excavations (motions) filled by spring water. Although they are frequently visible patrolling especially the perimeters of the wetlands, I'm reluctant to call anything so aeronautically and colorfully spectacular, 'common.'

Green Darner in flight

In their realm the Green Darners are lords of the air. They dominate  (from the Latin root dominat- ‘ruled, governed’, and dominus ‘lord, master’.) Compared to other dragonflies near the pond they tend to fly in assertive, purposeful loops rather than the inquisitive, tentative patterns of lesser species. 

Blue Dasher in flight

By comparison, Blue Dashers - well, not they're lesser, but smaller - dart about in their search for prey and in their social interactions.

Blue Dasher at rest

When a Green Darner zooms by the Blue Dashers get out of the way. They might take to perches during the turbulence.

Slaty Skimmer and Twelve-spotted Skimmer in initial reconnaissance

Dragonfly encounters are not always so one-sided. These two more evenly matched species jockeyed over boundaries and rights to a promontory.

The parties deliver terms

Initially the Twelve-spotted Skimmer displaced the Slaty Skimmer.

The Slaty Skimmer returns from retreat

The contest was not decided in one sally, and may have continued after I left the arena. Though fateful, the resolution did not appear to be fatal. Possibly they would find separate but equal opportunities.

A Choice of Blues

Earlier this summer pollen and nectar-seeking insects at the entrance to Halibut Point State Park were tempted by two different types of flowers blooming along a stone wall.

Chicory Cichorium intybus (foreground) and Viper's-Bugloss Echium vulgare (behind)

A bumblebee chooses to land on a flower at left center

I watched with interest as the pairings of pollination followed specific patterns. Bumblebees always went to the bugloss, never to the chicory.

Honeybee

Honeybees also visited the bugloss exclusively. My curiosity sharpened a bit, wondering whether the pattern resulted from taste, smell, flower structure, insect anatomy, or even color preference. After all, all blues are not alike.

Silver-spotted Skipper

The pattern continued with butterflies, which all preferred the bugloss flowers.

Cabbage White

Monarch

I decided that the more deeply colored bugloss made a lovelier association with the butterflies than the chicory would have. Was I abandoning science for aesthetics, or soft thinking? Wait a minute: why decouple  aesthetics, the sense of beauty, from intellect? Both those aspects of mind grow from the same evolutionary advance.

European Woolcarder Bee on chicory

Curiously, some other kinds of bees parted ways with the bumblebees and honeybees, going exclusively to the chicory flowers.

Bicolored Striped Sweat Bee, Halictidae

A little research online revealed that chicory is particularly attractive to short-tongued bees. Sure enough, that includes the Halictid family represented in the photo above. Conversely, bumblebees and honeybees are in the long-tongued family Apidae which forage well on tubular flowers.

Syrphus species of Syrphid family

Various species of Hover Flies (Syrphidae) joined the array of insects pollinating the chicory flowers.

Typocerus velutinus - Banded Longhorn Beetle

The nectar-seeking opportunists-or more properly, partners-in the chicory corollas included this Banded Longhorn Beetle.

One wonders whether the shape and color of the flowers are as influential in these attractions as they are to people. The sight of chicory has stimulated an impressive variety of words and poetry. Evocative words like azure.

Closer acquaintance with bugloss, however, reveals subtleties of form and color well beyond botanic interest, and perhaps ecstatic to certain bugs eyes. Red gets into the picture, pulling it to purple.

Down in the Grass

 

After flourishing unshorn for most of the summer the meadow is a complex and inviting feature in the Park landscape.

Monarch butterfly on clover

A variety of grasses and wildflowers have accomplished their cycle of flowering and seed production.

A Grass-Veneer moth

Aptly named Grass-Veneer moths, when disturbed, fly moth-like with wings outstretched in short fluttery bursts to a nearby perch.

At rest they blend in securely with the stem of their host.

European Earwig

An earwig on the hunt climbs through the diaphanous panicle of a seed head.

Seven-spotted Lady Beetle

Several species of lady beetles, juveniles and adults, similarly find foraging opportunities, such as aphids.

Notated Lady Beetle

Ursine Spurleg Lady Beetle

A lady beetle larva

Another juvenile lady beetle

Lygus nymph

Plant bugs of all ages, sizes, and finery inhabit the luxurious vegetation.

A Differential Grasshopper

A meadow visit wouldn't be complete without a grasshopper encounter.