Species of Symphrasinae (Neuroptera: Mantispidae) are ectoparasitoids of larvae and pupae of holometabolous insects, primarily of Hymenoptera in their larval stages. Herein we present the third case of an association between the mantidfly genus Anchieta Navás, 1909 with the order Hymenoptera. The hymenopteran species attacked by the as of yet undescribed species of Anchieta is Montezumia dimidiata Saussure, 1852 (Vespidae: Eumeninae), a predacious wasp that constructs mud nests. The association was observed in Peruvian Amazonia (near Tarapoto, San Martín), after rearing the mantidflies from a wasp nest. The biology and mimicry pattern with stingless bees of the reared Anchieta species is discussed.