Male cicadas are familiar for their unique loud airborne calls used in cour
tship and mate recognition. Extant Tettigarcta species in Australia are lit
tle-known relict survivors of a primitive Mesozoic cicada radiation which d
o not make loud calls and lack either the apparatus to produce them or the
auditory organs to detect them. Field studies on live insects in New South
Wales for the first time show that Tettigarcta produce low-intensity, subst
rate-transmitted acoustic signals in courtship. This habit seems to be a pr
imitive (plesiomorphic) feature.