Responses of all tested beetles to strong IR radiation.

Responses are given on the left Y-axis (blue bars) as latency until the threshold criterion for a change in flight direction had been reached (mean of the angle had to differ from the mean at stimulus onset by the double SD at stimulus onset). On the right Y-axis (red bars) responses are given as angle of flight direction in the 7th second after stimulus onset. On the X-axis the 14 tested beetles are listed. Significant differences between changes in angle caused by irradiation of the left and right body side exist in beetles 8, 9 and 14 (asterisks, data of beetles 11 and 14 tested with the Mann-Whitney U test, data for all others tested with the t-test, significance level for both tests was p ≤ 0.05; in beetle 14 only 5 stimulus applications per body side were made). In beetle 11 the threshold criterion was not reached when irradiation was carried out from left. (A) IR radiation given from the left. (B) IR radiation given from the right.