Fig. 4. Examples of stepping patterns. (A) Gap crossing, (B) undisturbed walking. Grey bars, ground contacts of antennae; coloured bars, swing movements of legs. FL, front leg (red); ML, middle leg (green); HL, hind leg (blue); l, left; r, right; ac, first contact of the antennae with the second footbridge; gc, gap-crossing step; te, tentative step; sh, short step. Normal walking steps are not marked. In A, the defined sections of gap-crossing behaviour (see Fig. 1) are separated by vertical lines.