Fig. 1. Mechanosensory stimulation directed to just part of the hind femur elicited rapid behavioural gregarization. (A-F) Histograms showing the frequencies of locusts falling into different categories of behavioural phase state after 4 h of mechanosensory stimulation directed towards the regions indicated in black on a hind femur. The white areas were painted over to prevent the activation of mechanoreceptive hairs. (G,H) In two control treatments, a hind femur was entirely painted over and either stimulated as in the other treatments or left unstimulated. N=12 locusts per treatment.