Fig. 1. Force measurement system of the beetle Pachnoda marginata. The system consists of a platform covered by sandpaper, force sensor, and videorecorder. 100 mm long crossbeam was connected to the force sensor on one side and supported on the other side. The height of the beam (D) relative to the sandpaper plane was adjusted to be 1-3 mm higher than the dorsal surface of the walking beetle. The force generated by the beetle was transferred by the beam to the sensor and monitored by the load cell force transducer and the signal amplified by the MP-100 system (Biopac system Inc. USA). The data were finally sampled and processed with the aid of a computer. A binocular microscope equipped with a video camera connected to a videorecorder was used to collect images of the beetle during the force measurements. From these images, the distance from the beetle to the sensor (X) was obtained. Force generated by the beetle F_B was calculated as F_B=100F_S/(100-X), where F_S is the force measured with the sensor.

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