Metrioptera brachyptera

In warm sunshine the calling song consists of long sequences of echemes repeated regularly at the rate of 4-7/s. Oscillographic analysis shows that each echeme normally consists of four syllables but, as the first syllable is usually short and often very quiet, the echemes are frequently described as being trisyllabic. Opening hemisyllables are usually present, though often quiet; the fore wings are held in an open position betweene chemes, so taht there is no opening hemisyllable before the first (quiet) closing syllable of each echeme but, most unusually for a tettigoniid song, there is usally an opening hemisyllable after the last closing hemisyllable. The closing hemisyllables usually last about 15-20 ms and are repeated within an echeme at the rate of about 35-55/s. The duration of a single echeme is about 75-120 ms and the interval between two successibve echemes is about 65-110 ms. In dull weather and at night the echeme repetiton rate can drop to as low as 2/s and the syllable repetition rate to 10/s; in such conditions the closing hemisyllables (of which the first is often louder than at higher temperatures) sometimes last as long as 90 ms and an echeme 400 ms or more. Under any conditions the echemes are very unifrom in structure and there are no microsyllables. [1]

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