Comparative phenology of four satyrine butterflies inhabiting dry grasslands in Sweden

The phenology of the satyrine butterflies Coenonympha pamphilus L., Lasiommata megera L., Hipparchia semele L. and Maniola jurtina L. was compared under seminatural conditions with Festuca ovina as the food-plant. Coenonympha pamphilus shows striking phenotypic plasticity as revealed by initiating cohorts at successive dates during the whole flight period. Growth rate is finely tuned depending on season, and larvae can hibernate in any of the three first instars, but also aestivate when 'surplus'time is available. Hipparchia semele and M. jurtina have reduced growth rates as last instar larvae at the beginning of summer. Lasiommata megera , which has an obligate bivoltine life cycle, shows the highest overall growth rate of all four species. Results suggest that egg size variation has consequences for the life cycles of these species.