— This article by Jerry Cates and Linda C., first published on 3 March 2010, was last revised on 6 July 2012. © Bugsinthenews Vol. 11:03(08).
—————————————–
A meadowhawk dragonfly, in the genus Sympetrum, sent in by Linda C., Southwest Austin, TX (taken in 2005)
This photo was sent in by Linda C., of southwest Austin, on 2 March 2010 (Texas Independence Day, for those who may not be aware). According to the data embedded in the image, the photo was taken on 7/16/2005, at 3:37 P.M., using a Kodak DX6490 Zoom Digital Camera. There is no indication, however, of the location. But we can see the dragonfly is resting upon the leaf of a… well, it happens to be the leaf of a pineapple plant. I know that because, after writing to Linda asking where the photo was taken, she wrote back the following:
“Jerry: I think this is a better one of the dragonfly which was taken on the leaf of a pineapple plant in my back yard. I’ve also attached a walking stick (?) that was taken about the same time, attached to the side of my son’s home in Boerne.
And I included two of my favorite wildflowers, the white poppy (or thistle) taken near Big Bend Ranch outside Presidio, and the umbrella flower… I think that’s what it’s called, I can’t find my book or poster! The latter grow in the hill country on dry, rocky outcroppings and along roadsides in the early spring but they’re so small I think most people don’t notice them. They’re only about 6-7″ tall and the little pink clusters atop a stem remind me of an ice cream cone.
Enjoy! and thank you for your interest, and especially for what you do… is this a profession for you or a passion or just a hobby? Lot of work.”
A meadowhawk dragonfly, in the genus Sympetrum, sent in by Linda C., Southwest Austin, TX (taken on 7/16/2005, 3:38 P.M., with a Kodak DX6490 Zoom Digital Camera)
The new image, shown at left (either photo, when clicked on, will produce a larger image for more careful inspection), is somewhat better than the first, yet both provide important perspectives on this dragonfly (I am posting Linda’s other photos under their respective taxonomical categories, elsewhere on the website) so both are posted here.
Let’s talk about dragonflies. First, though, it might be good to mention that dragonflies are in the order Odonata (Greek: odonto = “tooth,” from the fact that insects in this order have mandibles with teeth; however, these are not the only insects with toothed mandibles), which includes not only dragonflies (suborder Anisoptera) but also damselflies (suborder Zygoptera).
These insects are similar in many ways (see the material under the order Odonata for more information on these similarities), but differ in important anatomical features, many of which can be seen in a casual, visual inspection.
For example, the dragonflies rest with their wings stretched outward, as in Linda’s specimen. When a damselfly rests, it positions its wings backward, in line with the body.
Dragonfly wings are also quite different, in their anatomical structures, from those of damselflies. The wings of a damselfly attach narrowly to the thorax, while those of the drag0nfly attach robustly, along a broad area of connection that provides for excellent aerodynamics. When examining the wings of these insects, one notices that each front wing of a damselfly is “pinched” along its leading edge, at a point about one third the length of the wing, as measured from the point of connection to the thorax. The front wing of a dragonfly is pinched at a point about half the length of the wing. Both of these insects have a pterostigma (New Latin pter = “wing” + Latin stigma= “mark“), or wing marking, that is positioned near the leading edge of the wing, distal of (far from, i.e., out toward the tip of the wing) the wing root at the thorax. The pterostigma is a colorful, thickened cavity filled with blood. It serves an aerodynamic purpose (providing extra ballast at the wing tip, making it easier to move the wings up and down), and the hydraulic pressure in the veins leading to and from the pterostigma add rigidity to the wing structure. In the damselfly, the pterostigma is somewhat larger than that of the dragonfly.
Dragonfly wing venation, Linda C., Southwest Austin, TX, 07162005
Dragonfly pterostigma, Linda C., Southwest Austin TX, 07162005
Notice that the visible forewing of Linda’s specimen shows venation on the leading edge that is “pinched” about in the middle of the leading edge.
The pterostigma at the distal end of the leading edge is obvious, but not overly large. The legs of the dragonfly are armed with ominous, sharp projections that are used to grasp and hold prey.
The large, rounded head of the dragonfly has unusually large compound eyes, which occupy most of the head surface.
Note that both the right and left eyes touch, or nearly touch, each other on the dorsal surface of the head and across the face; in the damselfly, the eyes have a noticeable gap between them.
So, one should never mistake a damselfly for a dragonfly, or vice versa.
Certainly, no one who has read these words, and looks for the way the wings are held, the venation of the wings, and the structure of the eyes, will make such a mistake.
Meadowhawk Dragonfly, head and forelegs, Linda C., Southwest Austin, TX 07162005
Within the Odonata is a genus of small to medium sized skimmer dragonflies, the meadowhawks or darters (Sympetrum). The males and females are yellow-gold in color as juveniles, but mature males and some females become bright red on part or most of their bodies. Only the black darter (Sympetrum danae) is excepted from this rule.
Typically, then, if you see a red dragonfly, you can be relatively certain it is a member of the genus Sympetrum. Over 50 species of Sympetrum are known, all in the temperate zone of the northern hemisphere. They are often quite unwary of humans, and allow them to carefully approach, even to pick them up.
The skimmer dragonflies are called meadowhawks in North America, darters in the United Kingdom.
Oh, and I wrote Linda back, thanking her for the excellent photos, and explaining that this is my passion, my hobby, and my work, all rolled into one. “Do what you love,” one sage said wisely, “and you never have to work again. Every day is a holiday.” Truer words were never spoken.
—————————————–
— Questions? Corrections? Comments? BUG ME RIGHT NOW! Feel free to e-mail [email protected]. You may also leave a comment in the space provided below.
Like this:
Like Loading...
Related
