The larvae feed on grasses. I found them in Northern Greece near Katerini on Sorghum halepense.
Gegenes nostrodamus inhabits coastal areas, dunes, dry river beds, wetlands and other grassy and hot places. It is often found near the sea, but occasionally also in the interior. I observed adults in Northern Greece near Grevena in an periodically humid agricultural area with broad ditches in a river valley. Near Katerini I found numerous larvae along dirt roads near the coast.
Gegenes nostrodamus occurs in several generations during the warmer seasons. In the south it can be found throughout the year. The larvae live within a tube made out of a grass leaf where also pupation takes place. The males have stamping grounds in which they persecute other butterflies etc. in order to drive them away.
Gegenes nostrodamus is endangered in particular due to overbuilding of coastal ares for industry, traffic and settlements, but especially for tourism. Therefore the rather undemanding species is already severely threatened in many regions like Southern France. Agricultural expansion also causes damages, at least if no broad fallow structures remain.
Gegenes nostrodamus occurs very locally in the Mediterranean from Spain to Greece. Moreover it is found in north Africa and parts of Asia to India. Generally you will not find Gegenes nostrodamus and Gegenes nostrodamus together in the same site. Thus in Greece Gegenes nostrodamus is more common e.g. in the northern mainland whereas Gegenes pumilio is the only species e.g. on the east Aegean islands.
Hints on determination:
Gegenes nostrodamus is very similar to the closely related Gegenes pumilio, but it is larger. For example the last-instar larvae are much robuster than those of the other species. Gegenes nostrodamus has a medium position in size between Gegenes pumilio and Pelopidas thrax.