The distribution of a number of esterase variants have been studied in samples of Maniola jurtina from the Isles of Scilly. The results are compared with the data on spot distributions of samples of the butterfly taken from the same sites. Various points of similarity are seen between the patterns of variation shown by esterase and spotting polymorphisms. Thus, samples from within large islands tend to be more homogeneous than those from small islands, and discontinuities in spotting are reflected in discontinuities in the frequencies of the esterase morphs. These results are consonant with the conclusions of Ford and his co-workers with respect to the adaptive nature of the appearance of Scillonian populations of Maniola.