Males of the katydid Conocephalus nigropleurum (Orthoptera: Tettigonii
dae) shake their body to produce a substrate-borne vibratory signal in
the context of courtship and mate attraction. We measured the physica
l parameters of this tremulation signal and then tested its effectiven
ess in eliciting taxis by virgin females. We also investigated the rol
e of these vibrations in the choices made by females of larger males a
s mates, A search for correlations between male weight and vibratory s
ignal parameters revealed a strong negative relationship to inter-puls
e interval (ipi). In two-choice playback experiments females oriented
towards tremulation vibration when it was the only vibration stimulus
provided. In further playback experiments females also distinguished c
onspecific tremulation from a control vibration. When offered simultan
eous presentations of tremulation signals that differed in ipi, female
s moved toward the stimulus with the shorter ipi indicative of a large
r male, This is the first study to demonstrate that tremulation signal
ling by male katydids encodes critical information on body size, and t
hat females discriminate among different vibratory signals in favour o
f those indicating a larger male.