As another dragonfly migration season closes, it seems appropriate to consider one of the most notable features of these remarkable insects--their large, multi-veined transparent wings. These wings are frequently described in terms that imply fragility, such as "gossamer", "delicate", and "diaphanous". The poet Alfred Lord Tennyson wrote of a newly-emerged dragonfly that "he dried his wings; like gauze they grew", while Walter Savage Landor spoke of the insect's "filmy wing". But the delicate appearance of these wings is deceptive; tough and strong, they must support dragonflies as they perform agile acrobatics to pursue prey or chase away competitors; range far afield to seek territory or to disperse to more favorable habitats; or migrate hundreds to thousands of miles across continents or oceans. 

Dragonflies have been perfecting their flight tactics for a long time. The earliest known fossils of dragonfly-like insects are from the Carboniferous period; these 325 million year old eugeropterids, as they are called, were roughly similar in size to modern dragonflies, but they had 3 pairs of wings. The 3^rd pair was much reduced in size and it is thought to have acted as an airfoil to provide additional stability in flight. The meganeurid dragonflies which graced the skies during the Permian 250-300 million years ago more closely resembled our modern dragonflies but on a much larger scale; specimens found in Oklahoma and Kansas show wingspans of 27-28 inches. Fossils of what appear to be modern families of Odonata have been found beginning in the Jurassic period, about 145-200 million years ago.

While modern dragonfly wingspans are considerably smaller than the meganeurids', their wings are still an amazing feature. Many species are characterized by wings with dramatic patterns and colors, such as the intricate designs of Halloween Pennants (Celithemis eponina) and Filigree Skimmers (Pseudoleon superbus); the broad splotches of Saddlebags (Tramea species); the scattered dots of the Four-spotted Pennant (Brachymesia gravida); the wine-blush of a Band-winged Meadowhawk (Sympetrum semicinctum); and the intermix of powdery white pruinosity and dark patches of Widow Skimmers (Libellula luctuosa) and Twelve-spotted Skimmers (Libellula pulchella).

The wing veins and the cells and structures they form play active roles in flight, affecting air flow, elastic tension, bracing, friction, flexion, and shock absorption (they also have a practical use for taxonomists, as they can be used to identify many groups to genus). One can sometimes be alerted to the presence of a dragonfly by hearing the dry, rattling clatter of its wings in flight before the insect is ever sighted. Dragonfly wings can take a beating, and it's not uncommon for those of older adults to become tattered and shredded, sometimes with missing chunks bearing mute testimony to a close encounter with a bird or other predator. 

Migratory flights can also take their toll on a dragonfly's wings, and researchers with the Migratory Dragonfly Partnership have been examining wing wear on Common Green Darners (Anax junius) captured in different regions of eastern North America. These specimens were also subjected to stable isotope analysis to determine how far each insect had moved from the site where it developed as a nymph.  This study is in its final stages, and we hope it will reveal new information about just how well those "filmy wings" stand up to the amazing long distance flights these animals make annually.