Telenomus podisiAshmead andTrissolcus euschisti(Ashmead)are sympatric parasitoids of stink bug eggs. In field experiments,T. podisiparasitized significantly more egg masses on alfalfa,Medicago sativaL., than onhackberry,Celtis occidentalisL., andT. euschistiparasitized egg masses only on hackberry. There was no significant difference in the number of host egg masses parasitized 0–1 and 3–4.2 m above the ground byT. euschistiin black cherry,Prunus serotinaEhrhart, and hackberry trees. This is one of the few examples where sympatric solitary Hymenoptera that share a host resource subdivide their environment by host plant type. We suggest that the host plant type be considered when importing scelionids for stink bug control in classical biological control programs.