388 
Psyche 
[Vol. 85 
time. They grabbed, then released the insects. Additional observa- 
tions were then made with a microphone in the cage transmitting 
sounds to earphones worn by the investigator. A skink, Mahuya 
vittata caught and then released a sound-producing P. syriaca male; 
three geckos, P. h. guttatus each caught and promptly released 
sound-producing males of P. syriaca. These rejected grasshoppers 
were removed and immediately replaced by mute grasshopper 
nymphs of L. m. niigratorioides, equivalent in size to the rejected P. 
syriaca males; the nymphs were caught and immediately consumed, 
one by each gecko. These preliminary observations raised the ques- 
tion: were the sounds emitted by the grasshoppers a factor in their 
release? The following experiments were designed to answer this 
question. 
Materials and Methods 
Grasshoppers: Adult males of P. syriaca were field caught in the 
hills of Jerusalem a few days prior to experiments and were main- 
tained in 60 1 laboratory cages providing fresh plants, light and 
heat. As males were lifted from the cage for assignment to an 
experiment, the thorax was squeezed gently. Of 48 males squeezed, 
only three failed to produce sound. Half the sound-producing males 
were then silenced by releasing a drop of melted paraffin onto the 
closed mandibles; when it hardened, these males could no longer emit 
sound, though they hardly differed in appearance from untreated 
males. 
Fourth instar nymphs of Locusta migratoria migratorioides R & 
F maintained in the gregarious state in stock cages in the laboratory, 
served as additional controls. Their size, dark color and small wing 
buds provided a phenotypically reasonable facsimile of the brachyp- 
terous adult male of P. syriaca. These nymphs did not produce 
sound when handled. 
Predators: Ptyodactylus hasselquistii guttatus von Heyden was 
selected as the predator for the series of experiments. The candidacy 
of this gecko was supported by the following credentials: P. h. gutta- 
tus, a poikilotherm like P. syriaca, is at least partially sympatric 
with it and shares its biotope; it is an opportunistic insectivore; like 
P. syriaca, it emerges from its retreat in rock ledges and crevices in 
warm weather and has been known to feed during daylight (Werner 
1965; Perry & Werner 198 1 ); juveniles could handle a grasshopper 
