Trichotettix pilosula Stål, 1873

(2 males recorded) Songs of two males were recorded in the lab at 21°C. For one of these we had also obtained an earlier field recording at 11°C. The call is a rattle comprised of short sinusoidal pulses, paired in time, the pairs repeated over minutes without interruption (Fig. 32A). It evokes the sound of a minature one-stroke engine. Each pulse is only a few ms in duration (Fig. 32B) and never reaches an amplitude plateau.

In the lab a male (96-2) gave a pair rate of 8.5/s; his pair period was 117 ms with a pulse period of 27 ms. The other male (96-3) repeated pairs at 7.8/s; his pair period was 128.5 ms, pulse period 26 ms. In the field as a cold singer this same male (96-3) had a pair rate of only 3.3/s, the second pulse following the first (pulse period) by 55 ms.

At 21°C the pairs, but not the pulses, are resolved by human hearing. But at low temperatures each pulse becomes discriminable to the human ear and their paired nature very apparent.

The amplitude of a pulse rises quickly to form 7-14 intense waves with little or no plateau (Fig. 32B) and then there is some amplitude variation in a long decay. Possibly each pair constitutes a phonatome, i.e. the two correspond to one cycle of wing movement. But this notion is difficult to reconcile with the large number of teeth on the file (110, n = 1) (Fig. 20A). Alternatively several pulse pairs may be produced during one file run.

The spectrum is dominated by a single moderately narrow peak near 17kHz (Fig. 32C). Weak harmonics are present, a 2'nd and 3'rd but are more than 20dB below the top energy of the fundamental and hence not shown in Fig. 32 C.One of the males (96-2) produced its carrier at 17.5kHz (range 17.0-17.7). The other (96-3) was slightly lower at 16.3kHz (range 16.3-16.4). The mean principal carrier for 96-3 in teh field was 16.3kHz, exactly the same at both 11 and 21°C. [1]

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