In the presence of the red imported fire ant, Solenopsis invicta Buren, adult emergence of the parasitoid Lysiphlebus testaceipes Cresson from laboratory colonies of the corn leaf aphid, Rhopalosiphum maidis (Fitch), was reduced. Parasitoids abandoned an attack when ants were within a few millimeters and searched elsewhere, increasing search time. However, the increased searching time in the laboratory was compensated by a reduction in parasitoids' resting time resulting in similar levels of parasitism between the controls and the ant-infested containers. A major effect of the red imported fire ant was the removal and destruction of parasitized aphids. Ants began detecting parasitized aphids 6 d after parasitization and removed them to the ant colony. Honeydew production was reduced in parasitized aphids by 6 d and they resembled starved aphids. Behaviour; Agonistic behaviour; Associations; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology Lysiphlebus testaceipes (Aphidiidae); Hemipteran hosts; Rhopalosiphum maidis; Antiparasitism effects of Solenopsis invicta Solenopsis invicta (Formicidae); Defensive behaviour; Protection of hemipteran associate against hymenopteran parasite; Associations; Rhopalosiphum maidis (Hemiptera); Protection against parasite Lysiphlebus testaceipes Rhopalosiphum maidis (Aphidoidea); Associations; Solenopsis invicta (Hymenoptera); Associate antiparasitic interactions with Lysiphlebus (Hymenoptera); Hymenopteran parasites; Lysiphlebus testaceipes; Antiparasitism effects of Solenopsis invicta (Hymenoptera); Population dynamics; Hymenopteran associate effects