[Experiments on adult emergence rhythms in Carabid bettles]

The emergence times of the following species of Carabid beetles were investigated in a long day of LD 18/6: Agonum assimile Payk., Pterostichus angustatus Dft., P. nigrita F., and P. oblongopunctatus F.The hatching of the beetles was examined by means of an automatically controlled photorecorder.In one series of experiments flash-light was used for taking photographs. In a second series photographs were taken only during the light phase by the light of a fluorescent tube of the same type as used for the illumination of the breeding chamber.Both series of experiments produced no evidence of the existence of a typical emergence rhythm in the four Carabid species. In each species the number of beetles hatched per hour is slightly greater during the phtophase than during the scotophase. This difference was statistically significant only for P. angustatus. From this it is concluded that some Carabid species have a latent capability for synchronization of emergence by a light dark change.The sexes of P. angustatus show no difference in the distribution of their emergence times.