Fig. 1.

Experimental design for laboratory design 1. The black square with the number 1 represents the 20 × 20 cm black marker and its location for the first and the last measurements (forward/backward movements). Grey squares with the number 2–6 represent the successive locations of the marker for which swarm location was also recorded (forward and backward). Abbreviations: d, the calculated marker-swarm distance; S, the swarm