The state of ‘passive copulatory readiness’ is characterised by
females being mute but permitting copulations with males after
courtship. Observations of reproduction-related behaviour of Ch.
biguttulus females during daily periods of co-habitation with males
revealed no difference between the ages when females stridulated
for the first time and permitted male mountings (average age: 5.9
days vs. 6.0 days). In contrast, females were significantly younger
when they started stridulating compared with the age when they
performed first completed matings, which was indicated by
copulation times longer than 2 min (average age: 5.9 days vs.
7.6 days). For comparison, a previous study by Kriegbaum and von
Helversen (1992) with the same species reported first male songstimulated
stridulation at an average female age of 5.7 days.
Though we always placed five females together with six males,