Flag-tailed Spinyleg. These dragonflies are fairly common at large ponds, lakes, and prairie wetlands in our area. They are also seen along rivers. 

The Flag-tailed Spinyleg at left was eating a Common Buckeye butterfly. Flag-tailed Spinylegs like to lurk in the grass and nab passing butterflies. I have also seen them eating Hackberry Emperors, Pearl Crescents, Cloudless and Orange Sulphurs, and small skipper butterflies. The individual at left was photographed at the Caesar Creek prairie. 

This is a shimmery, teneral (newly-emerged) Flag-tailed Spinyleg. Photographed at Spring Lakes Park in Bellbrook (which has a great population of Flag-tailed Spinylegs). 

Flag-tailed Spinylegs fly from late June through early September.