[A recording method for locomotor activity of small insects]

The method described in this paper enables the locomotor activity of small insects to be recorded. It is based on variations in capacitance within a bridge circuit, the variations being due to movements of the animals. The method is adapted to the use of multi-channel action recorders, thus allowing a greater number of sensor units to be employed simultaneously.As an example of application, a comparison is made between the diurnal rhythmicity patterns of locomotor activity inDrosophila melanogaster andDrosophila azteca. Both species show maximal activity in the morning and in the evening.D. melanogaster is active throughout the middle of the day as well, butD. azteca, being adapted to an arid climate, shows a resting period during this time of day.