This dataset derives from cross-over experiments using ant worker rescue behaviour towards caterpillars of the socially parasitic butterfly from two host-ecotypes. The data comprise datasets collected from four 4 experiments 3 hours after testing and from 4 experiments 7 days later. They all include nest numbers, the order of retrieval ranked by the attention of nurse ants to the ant pupae, large larvae and small larvae and the adult Maculinea rebeli. The data give the rank order of test items as they were rescued in order to explain social status achieved in natural and unnatural host colonies. This dataset is part of the study of mimetic host shifts in an endangered social parasite of ants, which is a joint study of the NERC's Centre for Ecology & Hydrology (UK), the University of Oxford (UK), University of Bialystok (Poland), Polish Academy of Sciences (Poland) and UFZ Helmholtz Centre for Environmental Research (Germany). Detailed research method can be found in Thomas et al. (2012) Mimetic host shifts in an endangered social parasite of ants. Proc. R. Soc. B vol. 280 no.1751. (http://doi.org/10.1098/rspb.2012.2336) Full details about this nonGeographicDataset can be found at https://doi.org/10.5285/d6a8bc3d-b6fb-47bc-a693-612e2454cf50