1969] 
Willey and Willey — Social Displays 
291 
legs, (A) answers and turns his body parallel to (B), either facing 
the same or opposite direction. They then generate flutter-rasps in 
alternation three or four times. After this sequence, if they are 
facing in opposite directions they walk in opposite directions, and, 
a few inches apart, pause in an alert pose for up to several minutes. 
They then crepitate in opposite directions, one first and the other 
a second later. If they face the same direction, they may walk 
parallel and flutter-rasp in several sequences before parting. We 
have observed in the field and more often in the laboratory that the 
members of some pairs seem to be of equal aggressive strength and 
both try to point toward the other’s side. As a result, they circle 
around a common center and rasp in continuous alternation. Such 
bouts sometimes result in an attempt of one male to mount the 
other. This is followed with kicking by the mounted male and 
biting the dorsal carina of the pronotum by the mounting one. If 
a male tries to court another male, the signals of the courting male 
are usually turned off in mid-sequence by a responding flutter-rasp 
by the courted male. The courting male answers with a flutter-rasp 
and normal male-male interaction proceeds. However, males de- 
prived of opportunities to court females for a few days will complete 
courtship and mount a vigorously rasping male. Indeed, the only 
response certain to be made by a male in copulo is a flutter-rasp, 
serving to “turn off” courtship by another male. 
The flutter-rasp (Fig. 9) is produced by a rapid oscillation of 
the femur in contact with the tegmen. The effective sound produced 
is a broad-spectrum noise produced about 20 times per second whether 
the insect possesses one leg or two. In spectrograms of two-legged 
and one-legged males stridulating alternately, it is impossible to 
detect to which part of the sequence each belongs. Both may possess 
periodic double wave fronts probably produced by contact of the 
legs with the tegmen during both up and down stroke. Thus, as 
movies taken at 32 frames per second confirm, the flutter-rasp is 
produced by the legs moving simultaneously and in phase (if both 
legs are present). The burst of flutter-rasps rarely lasts more than 
0.5 sec. in an active interaction and often only three or four pulses 
are produced, which are then answered by a similar or longer train 
of pulses within a tenth of a second. The frequencies are difficult 
to ascertain, but the fundamental tends to range between 2000 to 
1 0000 Hz or higher with overtones at intervals of 5000 or 6000 Hz. 
These are the major frequencies from field recordings. The sound 
to the human ear is much more tonal than that of the crepitation 
