For the human ear, it is often difficult to tell precisely where a cicada song originates. The pitch is nearly constant, the sound is continuous to the human ear, and cicadas sing in scattered groups. In addition to the mating song, many species have a distinct distress call, usually a broken and erratic sound emitted by the insect when seized or panicked. Some species also have courtship songs, generally quieter, and produced after a female has been drawn to the calling song. Males also produce encounter calls , whether in courtship or to maintain personal space within choruses. 
(43) “Inquisition” (3/26/68)
The aliens assassinate a senator just as Vincent and Scoville are trying to convince him to join their crusade, leaving the Believers in hot water as an ambitious governent prosecutor seeks conspiracy and murder indictments against them.
Written by Barry Oringer.
Directed by Robert Glatzer.
Guest Stars: Mark Richman, Susan Oliver, John Milford, Stewart Moss, Robert H. Harris, Alex Gerry, Allen Joseph, Mary Gregory, Richard Merrifield, Burt Douglas, Bill Egan, Ernest Harada, Michael Harris, Lincoln Demyan, George Robotham.