1969] 
Willey and Willey — Social Displays 
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Calling. 
H ere there are important questions to be asked. It is obvious that 
the flight crepitation performs the aggregation function which is 
supplied by the femoro-tegminal vibratory stridulations of the male 
and female Acridinae (Otte, 1968; Faber, 1953; Alexander, i960). 
The crepitation by female A. conspersa may be equivalent to the 
response song of such acridines as Chorthippus females (Haskell, 
1962). Although Faber (1953) makes much of the wing buzzes of 
both sexes while they are are on the ground, we have never seen 
that this action produces any significant reaction with A. conspersa 
and it may only be a comfort movement. 
During the flight, the brightly colored hind wings flash red, 
orange or yellow depending on the phenotype (Willey & Willey, 
1967) and the flash is arresting to human eyes. The mechanism 
of sound production by the wing is still open to investigation. Until 
very recently the best guesses suggested that the sounds were pro- 
duced in a manner similar to that of a fan being snapped open and 
shut (Haskell, 1962). However, Otte (1968) described a possible 
instability of the wing membrane of loud crepitators when the wing 
is partially expanded which “pops” into the opposite configuration 
and could produce the crepitation. 
The presence of the femoro-tegminal solitary buzz excites interest 
also, since this signal seems to duplicate the function of the flight 
crepitation. Such sounds in the acridines are definitely implicated in 
the onset of pair formation and male location. Although we have 
never observed anything but ignoring or evasive action by females 
in response to the sound, the frequency of performance by solitary 
or recently repulsed males makes it unlikely that the buzz is com- 
pletely redundant or non-functional. Otte (1968) has reported fre- 
quent buzzing (“vibratory stridulation”) for A. sulphurea. Only 
once did he hear it in A. pseudonietana whereas we have heard it 
frequently and recorded it in three populations of this species. For 
some, but not all, populations of A. simplex , he reported similar 
buzzes, but none have been heard at all in A. xanthoptera and A. 
granulata. Buzzing also was recorded for A. conspersa , but no 
details were given. Further, Otte believes that the buzz is a part 
of the courtship, a contention which we find not entirely satisfactory, 
since we find that it it predominantly given under situations of soli- 
tude, refusal or loss of visual contact (as Otte also admits). It 
may, then, be a dual purpose sound, evolving from a call perhaps, to 
a courtship interruption sound (pair-reforming). Secondly, the 
