To adapt to the seasonal changes in the environment of our planet, animals have evolved an internal circadian clock. For example the seasonal changing floral resources are a great challenge for the honeybee. The circadian clock is involved in processes like the honey bees’ time compensated sun compass orientation and the age related assignments of tasks in the bee hive. While foraging bees display strong circadian activity rhythms in their behavior, nursing bees show no such circadian rhythmicity.The molecular basis for this rhythm is a negative feedback loop consisting essentially of the four clock genes period, cryptochrome-m, cycle and clock. But other factors like the neuropeptide PDF (Pigment Dispersing Factor) seem to be also involved in the molecular clock of the honey bee.The main aim of my phd-project is to further characterize the circadian clock of honeybees (Apis mellifera) on the anatomical and molecular level and investigate the behavioral output of the honeybee clock by locomotor activity monitoring. Of special interest is here the locomotor activity of individual bees in the social context of a bee hive. Also part of my project is the characterization of the circadian clock of other insects which are research organisms in the collaborative areas of the SFB 1047. For example the solitary living red mason bee (Osmia rufa) and the pea aphid (Acyrthosiphon pisum).