Length: 42-55 mm
To identify a damselfly as Lestes vigilax, look for great length, a metallic green thorax with brown shoulder stripes, and dark tibiae.
The back of the head is dark, but may lighten in apparent color as pruinosity develops.
Swamp Spreadwing may be found at acidic habitats that some other species shun. Wetland ponds, lakes, and sluggish streams are the preferred habitats.
Although common in some surrounding states, in West Virginia this species is rated S2, indicating 6-10 documented locations. Thus far most collections of Lestes vigilax have been from eastern counties, but continued field studies will probably show that this species is not so uncommon in West Virginia as the S2 ranking would indicate.
Swamp Spreadwings will be active in almost any month the weather is not too cold, and are typically seen in the Mountain State from late May through October.
Early research in sperm displacement examined the mating of Lestes vigilax, the first Spreadwing to be studied in terms of this phenomenon (Waage, 1982). Sperm displacement was not as dramatic as in the cases of families Coenagrionidae and Calopterygidae. Still, Waage did indicate that the last male to mate with a female did have an advantage over other males that had mated with her, both by removing their sperm, and by placing his own sperm closest to the area where fertilization actually takes place.