Fig. 4. Time-averaged plume boundaries of point-source and wide plumes with the track of the cockroach head (solid line) and the tips of the left and right antennae (broken lines). (A) Upwind track of a P. americana male in a point-source plume. Shallow v-shaped lines indicate the position of the left and right antennae and the head position at important points along the track. The timing of these points, with respect to the zero time at which the male entered the field of view of the camera, is indicated in association with each antennal position. The time signatures represent: 0.56 s, contact of the left antenna with the time-averaged plume boundaries; 0.73 s, loss of contact between plume and the left antenna; 1.06 s, initiation of left turn; 1.19 s, re-contact between the left antenna and the time-averaged plume. (B) Upwind track of a P. americana male in a wide plume. In each example the upper box represents the overhead view of the track. An exploded view of the indicated short section of the track shows the cockroach head (solid line) and tips of the left and right antennae (broken lines). Below is the exploded view from the side. Cockroaches are traveling upwind from right to left. Details as per Figs 1 and 3.