SLOWED MOTION ANALYSIS OF 
SOUND PRODUCTION IN THE 
GRASSHOPPER ARPHIA SULPHUREA 
(ACRIDIDAE: OEDIPODINAE) 
By Robert B. Willey 
The University of Illinois at Chicago Circle, 
Biological Sciences, P.O. Box 4348, Chicago, IL 60680; 
and the Rocky Mountain Biological Laboratory, 
Crested Butte, Colorado 81224 
From the time of the classic studies by Pierce (1948) and 
Pasquinelly & Busnel (1955), there have been many attempts to 
slow the movement of insects visually so that the sounds they pro- 
duce can be analyzed biomechanically. Usually these efforts have 
been directed towards “elytra!” stridulation (Bailey, 1970; Bailey 
Sc Broughton, 1970; Morris Sc Pipher, 1972) by the use of photo- 
graphic stroboscopy and oscillography of potentials from electrodes 
or sensors on the moving parts or in the muscles governing the 
movements. Also the Hall-effect has been used to plot oscillographi- 
cally the movements and acoustic signals simultaneously. This has 
been effected in an insect as small as Chorthippus mollis by means 
of permanent magnets attached to the moving femur, which in turn 
produces a changing voltage in a Hall-generator fixed on the back 
of the insect between the wings (Eisner, 1970, 1974a). Miniature 
magnetometers of this type have been used in human vocalization 
movements also (Hixon, 1971). Other workers have reported 
routine use of television tape systems with simultaneous sound re- 
cording and/or sound visualization (review: Wussow et al., 1974). 
All of the methods so far mentioned have disadvantages. 1 ) It is 
difficult to adjust a stroboscope if motions are non-cyclical, very 
brief in duration or variable in frequency or velocity. 2) Electrodes 
and magnetic sensors may restrict or disturb normal behavior of 
small organisms. Also, simultaneous recording of both femora in 
motion using the Hall-effect apparatus has not proved feasible 
(Eisner, 1974a). 3) The nature of the television trace mechanism 
causes a time delay distortion between the upper and lower portions 
of the picture when the tape is stopped for analysis. A single video 
field represents more than 16 msec which is unsuitable for analysis 
of motions taking less than 50 msec to complete (Steinberg Sc 
Willey, 1974; Wussow et al., 1974). However, for gross motion 
studies, the television tape system is the least expensive and most 
useful of all compound methods. 
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