Fig. 3. Mechanical stimulation of a hind femur of locusts unable to move their legs produced only a small change in behavioural phase state. Distribution of P_sol values obtained after 4 h of mechanical stimulation in restrained locusts (N=77). 45% of restrained locusts remained highly solitarious (P_sol>0.95) after mechanical stimulation, but more animals showed some increased gregariousness compared with unstimulated controls. The asterisk indicates the degree of significance (t-test) of the rank normalised data against the controls in the previous experiment. ^*, P<0.05.