The influence of restricted feeding time on the subsequent survival of adult Aglais urticae and Inachis io during diapause was tested in the laboratory. Abdominal lipid weight increased in the first 7 days of feeding by A. urticae and up to day 15 in I. io. Lipid as a proportion of dry weight also increased during this time. Individuals of both species feeding for 0–3 days began overwintering at significantly lower weights, and percentage weight loss during overwintering was more rapid than for those feeding for longer periods. Differences in fresh weights at the beginning of the overwintering period are reflected by differences in overwintering survival. In A. urticae, all 0–3 day feeders died in less than 150 days, in contrast, over 75% of 7–30 day feeders survived this period. In I. io, all 0–1 day feeders died within 160 days, less than 50% of 3 day feeders survived, whilst over 90% of7–15 day feeders were alive after this time. In I. io individuals feeding for one day, fresh weight is correlated with survival time suggesting that a larger body size may enhance survival time if feeding time is restricted.