Using the African diederik cuckoo Chrysococcyx caprius and four sympatric passerine foster species in the subfamily Ploceinae, we show that nestling cuckoos are infested by feather lice and mites derived from the ectoparasite fauna typical of the foster species. Adult cuckoos had five species of lice and mites normally found on ploceines, which demonstrates that these ectoparasites are able to survive on foreign hosts. This is the first record of persistence of passerine ectoparasites on a cuckoo. Adult diederik cuckoos also harboured four species of mites and lice specific to cuckoos; since these were not detected on nestlings, cuckoo-specific lice and mites apparently transfer to cuckoos after they leave the nest. Contrary to prediction, ectoparasites with a life cycle involving a permanent association with their host (feather mites and lice) were more likely to transfer to cuckoo nestlings than ectoparasites which spend part of their life cycle away from their host (haematophagous mites and phoretic skin mites). New host records are established for the lice genera Brueelia, Cuculoecus, Machaerilaemus, Myrsidea, Philopterus as well as for the mite species Microlichus americanus, Ornithonyssus bursa, Ornithocheyla megaphallos, Pellonyssus reedi, Pteronyssoides passeris, Pternonyssus glossifer, Trouessartia baupi, T. carpi, Xolalges plocei, X. scaurus and the mite genus Passeroptes.