1969] 
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301 
tus (Rehn & Grant, i960, and this present paper). Indeed, R. 
Alexander (i960) reported that he had recorded the female response 
song in Chortophaga viridifasciata an oedipodine. It is possible that 
virgin females in many species signal the courting males if they are 
at a distance or if the view of the male is obstructed. However, the 
probable redundancy of crepitation and response stridulation may be 
contributing to a selection against the weaker signal. The lack of 
consistent data on virgin, receptive females plus data on individual 
males of known age makes the courtship interaction of most oedi- 
podines an unclear picture at best. 
CONCLUSIONS 
Social interaction in Arphia conspersa can be divided for con- 
venience into two separate systems of communication involving 
specific methods of signaling : 1 ) communication at a distance and 
2) communication during physical contact. In these grasshoppers, 
signaling from a distance involves visual and acoustic modalities. 
Signaling during contact is mainly tactile. Some chemosensory input 
generated by the receptive female may be present but such an explana- 
tion is not necessary for any of the observed signal-response systems. 
Signals at a distance include sounds emitted by the wings under 
certain circumstances during flight, sounds produced by movements 
of the hind femora over the tegmina, and soundless but specialized 
movements of the hind legs during specific interaction sequences. Other 
sounds are emitted occasionally, such as mandible-clicking, wing- 
snapping, ground-scraping and -tapping, but we have never observed 
any evidence of meaningful reaction by other grasshoppers except 
avoidance reaction in the case of some wing-snapping. Most of those 
motions which seem to have communicative function combine a flash 
of bright color with a sound produced by the same motion. We are 
investigating the relative importance of the visual and auditory 
portions of the signal and have some evidence that the sound and 
color are intensifies and modifiers in the several combinations such 
as the rasp, buzz, chirp and squeal. The resulting visual flicker plus 
the buzzing sound should be very attention-getting to grasshoppers 
in which auditory flicker fusion probably doesn’t occur until pulse 
rate frequencies reach the order of 200/second (Haskell, 1961) and 
visual flicker fusion may be more than 50/second (Dethier, 1964). 
However, the question of flicker perception is still an open matter 
and grasshoppers may have even higher rates of flicker resolution 
(Dethier, 1964). 
