200 
Psyche 
[March 
A B C 
50 ~ ~ 100 i&0 200 250 
TIME (msec) 
Fig. 15. Sound spectrograms of one chirp of Adclium pustulosum (the 
chirp is that lettered BC in Fig. 14 A, and shown expanded in Fig. 142? 
and C) . In each spectrogram the first syllable is on left and second syllable 
on right. Spectrograms were made from recorded sounds replayed at x /% 
speed. Top spectrogram: wide band analyzing filter (effective bandwidth 
2400 Hz, with effective time response of 0.375 msec); bottom spectrogram: 
narrow band analyzing filter (effective bandwidth 360 Hz, with effective 
time response of 2.75 msec). Beside the top spectrogram are shown energy 
distribution profiles, corresponding to time transects lettered on the spec- 
trogram itself. 
indirectly, from the tape-recorded sounds of the beetles. This was 
done by monitoring the playback of the recordings with a microphone 
pickup and oscilloscope (the same microphone as used previously for 
recording of the chirps), and adusting the intensity of the playback 
until the induced oscilloscope signal matched that initially elicited by 
live beetles held i cm from the microphone. The intensity of the 
adjusted playback was then measured with the Sound Level Meter 
positioned at the site of the microphone, and found to be 65 db 
(relative to 0.0002 dynes/cm 2 ). 
Detailed analysis of the oscillograms showed that the beetles ap- 
parently do not scrape both ridges with equal consistency during 
stridulation. In fact, stridulation appears to involve predominant 
scraping of only one ridge during downward deflection of the ab- 
