EN
In many studies on medical entomology Lucilia caesar (L.) and L. Illustris (Meig.) have been treated together as the „L. caesar group". The present article shows that there are considerable differences in the ecology of the two species. L. illustris extends its range about 600 km further north, occurs seasonally about two weeks earlier, is less synanthropic, is more heliophilic and has a more extensive distribution in the zones of the archipelago than L. caesar. The diurnal and annual fluctuations of the population desnsity of the two species are almost identical, however.