The specificity of the ichneumonid D. pulchellus towards its usual host-pupa, A. assectella , is tested using 3 other lepidopteran species, Plutella xylostella, Ephestia kuehniella and Plodia interpunctella . The female wasp spontaneously parasitizes the pupae of A. assectella and P. xylostella whether they are inside their cocoons or not (naked pupae) and whether the larvae are reared on their host plant, Allium porrum or on a synthetic diet. P. interpunctella and E. kuehniella pupae are not parasitized even if they are covered with very attractive larval frass of A. assectella , whether they are inside their own cocoons or not. These 2 species are only parasitized if they are introduced in a cocoon of A. assectella or P. xylostella. none