Synopsis of experiments.

Results of all experiment are listed excluding the experiments in which the IR organs were covered with aluminum foil (given in Fig 5). Data of the experiments with the 14 beetles tested with strong IR radiation–already provided in Fig 4 - were recalculated to meet the evaluation of the other data (see Material and Methods: last paragraph of Data analysis). Undisturbed flight sequences in the seconds before stimulus presentation were also included (straight flight without stimulus, 4 flight sequences per beetle were evaluated). Changes in flight direction are grouped in 6 classes of angles. N gives the number of tested beetles; n gives the number of stimulus applications per body side.