Trissolcus japonicus (Ashmead) is an Asian egg parasitoid of the brown marmorated stink bug, Halyomorpha halys (Stål). It has been under study in U.S. quarantine facilities since 2007 to evaluate its efficacy as a candidate classical biological control agent and its host specificity with regard to the pentatomid fauna native to the United States. A survey of resident egg parasitoids conducted in 2014 with sentinel egg masses of H. halys revealed that T. japonicus was already present in the wild in Beltsville, MD. Seven parasitized egg masses were recovered, of which six yielded live T. japonicus adults. All of these were in a wooded habitat, whereas egg masses placed in nearby soybean fields and an abandoned apple orchard showed no T. japonicus parasitism. How T. japonicus came to that site is unknown and presumed accidental.