Very interesting. You must have the emerald ash borer, Agrilus plannipenis or some other native Agrilus in the area. The chalcid is a female of Balcha indica (Mani & Kaul) (Eupelmidae: Calosotinae). As the species name implies, this parasitoid was described from India and was introduced accidentally into North America from somewhere in southeast Asia sometime prior to 1994. This is when it was first collected in eastern Virginia. Although males are known from the Old World only females have been recovered in North America, indicating a parthenogenetic form was introduced. This is known from some other introductions and makes establishment very easy because all you need is one female. Since then it has because a parasitoid of the emerald ash borer, another invasive, though it probably hits any Agrilus. The association with aphids is interesting. It may have been trying to get some honey dew for sustinence.

The emerald ash borer was found a year ago in the same county. I haven't heard anything more this year. I hope they manage to stop its invasion in this area.
This is so interesting! I wish I had more photos.
Your comments are extremely valuable.