The cocoon from which this Ichneumon emerged was found outside our front door in early January, 2019. I was told that it is likely an Enicospilus species. Ian Gauld described 'The species of the Enicospilus americanus complex in eastern North America", 1988. I don't have the instruments to follow his diagnostic key, but of the seven described species, E. american is the only one that is found in my area, doesn't kill its host larva before it can spin a cocoon, and chooses a host that spins a thick walled cocoon, as seen in one of the two photos.