I used radiotelemetry to study habitat use and foraging activity of 27 Myotis myotis from a nursery colony in Bavaria (West Germany) from May to August 1987 and June to August 1988. Adults spent most of the night flying in individual but nonexclusive areas and showed high specificity for forested habitats. Pregnant females had the longest foraging times. On cold and rainy nights, foraging time was reduced and bats of both sexes and all reproductive classes often used alternate day roosts. Radio-tagged juveniles progressively increased time and distance away from the nursery roost and foraged independently from their mothers. Carabid beetles were the most abundant prey (sampled on 12 nights), but their availability was not affected by weather.