Abstract Butterflies of the genus Melinaea have conspicuous warning colours and are thought to be the prime distasteful models in many cases of mimicry in the Neotropics. Colour pattern variability has made systematics challenging and previous studies have found little to no genetic differentiation. This paper provides detailed descriptions of the immature stages of seven Melinaea taxa from north-eastern Peru, including distribution and host plant use, in addition to measures of genetic differentiation using microsatellite markers and mitochondrial sequences. Development time and immature stages were similar, making it difficult to elucidate taxonomy based on larval morphological characters. All taxa used Juanulloa as a host plant (Solanaceae), except Melinaea ‘marsaeus’ mothone, which occurs at higher elevations and used Trianaea (Solanaceae). The seven taxa show virtually no mitochondrial divergence, suggesting a recent radiation. Microsatellite markers, however, revealed distinct genetic clusters and evidence of admixture, demonstrating a complex diversification history. Ecological and genetic differentiation observed for Mel. ‘marsaeus’ mothone prompts for a taxonomic status revision to Melinaea mothone mothone and the taxonomic status of Melinaea ‘satevis’ tarapotensis remains unclear. Clearly, further work is needed to clarify the systematics and to shed light on the processes driving speciation in this genus.