What is the Hine's Emerald Dragonfly?
Dragonflies are insects of the Order Odonata, which means "toothed jaws," and the Hine's Emerald Dragonfly (Somatochlora hineana) belongs to a group of dragonflies with emerald eyes, referred to as the "Emerald Family." These are slender dragonflies with metallic green, brown, or black bodies, and they usually have emerald green eyes. The genus Somatochlora is the largest subgroup, and these individuals generally have stripes on their thorax. The toothed jaws of a typical dragonfly are shown below.
Like their namesake gems, Emeralds are generally scarce and difficult to find," says S.W. Dunkle in his book "Dragonflies Through Binoculars" (Oxford Press). Wingspan of an adult Hine's Emerald Dragonfly is from 2 1/2 inches to 2 3/4 inches, and the body measures about 2 1/2 inches long. They are strong and aerobatic flyers, and can spend hours aloft catching small prey insects, generally feeding in flight. In the case of an unusually large insect, they may perch briefly to finish the meal. Mosquitoes, deerflies, flying ants, and even smaller dragonflies are on their menu.
What about its anatomy?
As with all other insects, the body is divided into head, thorax, and abdomen. They have one pair of antennae located on the head, three pairs of legs, and usually one or two pairs of wings in the adult state. All insects are air-breathing and they are members of the Phylum Arthropoda, a group that represents the most dominant animals on the planet, with over a million species described and an estimated 9 million remaining to be discovered. Arthropods have a hardened exoskeleton (our skeleton is internal, so it is an endoskeleton) and their body plan is based on a series of segments. The abdomen of the dragonfly, for example, clearly reflects the segmental body plan of all arthropods, from crayfish to spiders to preying mantises (by the way, spiders are NOT insects). Finally, arthropods have jointed appendages. One can learn about the anatomy of the Hine's Emerald Dragonfly by reassembling the parts show below. Use the title drawing on the home page as a guide (useful hint: the thorax consists of three segments, and the two pairs of wings are associated with the first and second thorax segments; the first segment is rather small).
What are its distinguishing features?
If you spot a relatively large, dark-colored dragonfly showing strong flight characteristics, look for emerald green eyes. The green is best seen in reflected sunlight.
Next look for two yellow or cream-colored stripes arranged obliquely on the thorax. In juvenile Hine's Emerald Dragonflies, as shown below in Fig. A, the stripes are distinctly yellow. As the individual ages, the stripes become cream-colored, and the anterior stripe may even appear white in an old specimen (Figs. C and D). There is also a small, triangular, splash of color on the second abdominal segment (the first segment is small). Figs. C, D, and F show the yellow spot on the second abdominal segment.
Fig. B shows the terminal abdominal appendage (clasper) of the male, while the female's terminal appendages are shown in Fig. C. The unique shape of the male clasper is perhaps the most definitive feature in identifying the Hine's Emerald Dragonfly.
NOTE: As an endangered species, the Hine's Emerald Dragonfly must be studied without capture. A good pair of close-focus binoculars is essential (such as Eagle Optics' "Ranger" by Celestron). Final identification is best made when the dragonfly is perched. This takes patience!
Photogallery of the Hine's Emerald Dragonfly
Photographs were taken at The Ridges Sanctuary on sunny days, when dragonflies are most active. The lens of choice was a 200 mm. Micro Nikkor mounted on a manual focus Nikon F-2 body, and the camera was generally hand held. Only natural lighting was used. Fuji Reala print film was used in this series (ISO 100). Fig. A shows a dorsal view of a male Hine's Emerald Dragonfly and Fig. B. is a dorsal view of an older female. The gray abdomen of the female may be a consequence of egg-laying activities, in which debris adheres to and stains the abdomen. Figs. C and E are lateral views of males, while Fig. D is a female (note the two dorsal appendages, called cerci, at the tip of the abdomen). Fig. F shows a copulating pair, with the male at the top. This is the so-called "wheel" configuration characteristic of mating in many dragonflies. The male clasper is indexed with and locked behind the head of the female, while she grasps the male's abdomen. The reproductive openings are brought into alignment and sperm are transferred into the egg chamber of the female, where fertilization occurs. Copulation can last for up to an hour.
Fig. A shows the head and thorax of a juvenile S. hineana. The eyes haven't acquired their emerald green coloration, and the thoracic stripes are bright yellow. Fig. B shows the tripartite clasper of the male, while Fig. C. shows the terminal abdominal appendages of the female. The long cerci are paired and extend posteriorly. At the left, appearing as a "rudder," is the "egg-laying spout" or "ovipositor," which plays a role in the deposition of eggs in vegetation or muck.
And finally, what beautiful green eyes you have!
Click Here To Go To Page 2