Females possess a very long ovipositor, so the wasp pictured here is a male. In this family look for the abdomen inserted very high on the thorax, and a noticeable "neck" where the head attaches to the thorax.
Photo location: Smoke Hole, West Virginia.
Note that this both the family page for Gasteruptiidae and the genus page for Gasteruption sp.
American Insects site