‘PROTEST’ SOUNDS OF A GRASSHOPPER; 
PREDATOR-DETERRENT SIGNAL?* 
S\R\L A. Blondheim and Eeiezer Frankenherg 
Zoology Dept., Hebrew University of Jerusalem 
Jerusalem, Israel 
Introduction 
Some animals emit sounds when grasped or handled. Referred to 
as alarm, protest, distress or disturbance signals — the sounds 
themselves, the behavior accompanying their emission and the 
mechanisms responsible for their production have been described, 
analyzed and discussed (Haskell 1974). But only recently have 
experimental data become available in support of the oft-stated 
hypothesis that these sounds may startle a predator into releasing a 
noisy morsel (Bauer 1976; Smith and Langley 1978; Masters 1979; 
Buckler et al 1981 ). 
The grasshopper Pareuprepocneniis syriaca Giglio Tos (Acridi- 
dae) when grasped, immediately begins to chirp (the biology and 
acoustic behavior of this grasshopper will be described separately). 
Though there are individual differences in intensity and quality of 
the sounds, males have a greater tendency to squeak while females 
tend to click. Emission of the sounds is easily observed to 
correspond to movements of the mouthparts; if the labrum is lifted, 
the mandibles can be seen rubbing against one another to the 
rhythm of the chirps. Immobilization of the mouthparts prevents 
sound emission. 
It had been observed in our laboratory that on casual feeding of 
this grasshopper to representatives of several lizard families (La- 
certidae, Scincidae, Gekkonidae) the grasshopper was captured, 
then promptly released. A male grasshopper introduced into the 
cage of the lizard Lacerta cianfordi was caught head-first and held in 
the mouth of the lizard for several seconds, after which the lizard 
slowly opened its mouth and the grasshopper fell free. Several addi- 
tional grasshoppers of this species were offered to two Euhlepharis 
macularius, a gecko from Pakistan present in the vivarium at the 
* Manuscript received by the editor July 15. 19H3. 
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