Samples of populations of the autumn brood of T. abeona were examined for a number of colour and pattern characters. Morph-ratio clines in two patterns and two colour traits were detected. Three of these clines occur in the one small part of the species range. The decrease in frequency of the two pattern traits is accompanied by a decrease in size of the marking, when present. Limited genetic data show that one of the colour traits is sex-linked, and suggests that the others may be under simple genetic control. The data suggest that secondary intergradation, following a period of allopatry, has produced the observed distribution pattern.