Have you ever looked closely at a dragonfly’s legs? A dragonfly has six legs that are attached in pairs to its thorax. The main parts of the leg are the upper leg or femur, the lower leg or tibia, and the foot or tarsus, which is made up of three segments and ends with a pair of claws. The legs are covered with spiky hairs and fulfill a variety of functions, including perching, catching and holding onto prey, and cleaning its mouth and eyes.
The first photo is a close-up view of a Uhler’s Sundragon (Helocordulia uhleri) that I spotted on 4 April near a creek in Prince William County, Virginia. You get a really good view of one of the middle legs of the dragonfly, including the way that it bends at two joints and the way the tiny claws are used to hold onto the perch. I can’t be sure, but I believe that the dragonfly may be using one of its front legs to wipe its large compound eye. If you click on the photo, you can see some of the thousands of ommatidia, the faceted optical units that allow a dragonfly to see in almost 360 degrees around itself.
In the second photo, you can see that the sets of legs are of different lengths. The back legs, which are the longest, are the ones that are most often used to catch and subdue prey. The front leg nearest us, does not seem to be used and the moment for perching and the “elbow” appears to be touching the eye. At first I thought that this was merely an awkward perch, but the more I look at the photo, the more I think that the dragonfly is cleaning its eye.
The final photo, which was actually the first of these photos that I took, shows the entire body of the Uhler’s Sundragon. The Uhler’s Sundragon is visually similar to the Selys’s Sundragon, the first dragonfly that I spotted this year, with the notable difference that the Uhler’s Sundragon has little orange patches at the base of its wings, as you can see in the photo, that are not present with the Selys’s Sundragon. If you look at the front legs, it appears to me that the dragonfly was using both of them initially for perching—its “elbow” does not appear to bent as it was in the middle photo.
This post was a little more “geeky” than usual, delving deeper into dragonfly anatomy than I usually do. I think it is fascinating to try to observe and understand the behavior that I see in my subjects and hope that you may also find these details to be somewhat interesting.
© Michael Q. Powell. All rights reserved.
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Mike Powell 