1969] 
Willey and Willey ■ — Social Displays 
303 
in western North America. The nymphs overwinter and emerge as 
adults soon after the snows melt. The active breeding season above 
8,000 feet elevation near Gunnison, Colorado, is short and isolated 
temporally from that of other species which overwinter only in the 
egg stage. 
Social communication includes silent motions of the hind legs by 
both sexes, as well as various frictional sounds which are produced 
only by the male which passes the femora over a specialized file on 
the tegman. Each of these patterns of movement delivers a visual 
and acoustic flicker stimulus which is distinct in pulse rate frequency 
(PRF) from all the other signals. Silent single flicks of the hind 
femora disclose the bright yellow (in males) or brownish yellow (in 
females) abdomen and serve as non-specific advertisement of presence. 
The sounds produced by unitary or multiple leg movements can be 
single chirps (courtship approach), multiple chirps (PRF up to 
5/0.3 sec., probably a pre-mounting song), flutter-rasp (PRF— 20 
single or double pulses/sec. , prevention of aggression among males), 
and buzz ( PRF= 1 10-120/sec., after repulsion by the female, after 
losing track of the female, or after hearing another courtship se- 
quence). A squeal is produced in response to severe disturbance, such 
as capture, injury, loud multiple-pulsed sounds, etc. The brightly 
colored wings alone also produce pulsed sounds (PRF=45-5o/sec., 
crepitations) during spontaneous flights by males and sometimes 
females. 
Females have not yet been observed to stridulate, though they 
have a normal stridulatory apparatus. They reject courtship in 
several ways, ranging from merely closing the subgenital plate to a 
threat display which involves raising the hind femora past the 
vertical position and waving the tibiae in a slow and deliberate 
manner. Acceptance of the male ordinarily is passive, but active 
solicitation has been observed. 
This wealth of definitive signals and responses makes study of 
species in this genus important for communication research and the 
evolution of communication systems in insects. 
PROTOCOL (Recording and Missilyzer transfer data) 4 
Fig. 2. Crepitation = AKG microphone with parabola, distance 3 feet, 
Nagra input —20 db, 15 ips, sun thermometer 40°C, Gothic about 9600 
feet; Missilyzer input VU — +1/+2, output VU —6/— 5, ML 7.5. 
Fig. 3. Clicks produced by an Exacta camera reset mechanism. 
4 A11 recordings were at 15 ips, patterns normal, displays equivalent to 
normal speed (HH input and output), ips — inches per second, analysing 
filter bandwidth for all displays = 600 Hz. 
