For tree crickets the temporal pattern of pulses is extremely precise. One wingstroke is generally exactly like the next. The plot on the left shows the distribution of pulse periods for 568 pulses from 10 secs of the song of a male tree cricket. The variation is very small and about 90% of the pulse periods differ by less than 0.5 ms. Because insects are poikilothermic and contraction rates of muscles are temperature dependent, the temporal rhythms of almost all insect songs vary with temperature. The plot on the right shows Tom Walker’s data from three species of tree crickets where the pulse rate is plottted as a function of the temperature. The relationships are linear with temperature and different species have significantly different functions. What is not clear is how the variation in pulse rates changes with temperature. One important aspect of the temperature dependence is that females use the pulse rates of the songs of male in making mating decisions, at least on a gross level the pulse rates function as an isolating mechanism. Interestingly, the females response to pulse rates is coupled to temperature in exactly the same way, and a female quadripunctatus at about 30oC can be attracted to a celerinictus male singing at about 22oC.