118 
Psyche 
[Vol. 95 
female’s eye (Fig. 1); in at least some cases (probably often, but 
certainly not always) the leg hit against the arista of the female’s 
antenna. 
Tapping occurred in short bouts averaging 5.0, 4.6, 3.8 and 4.3 
taps/ bout in four different pairs (range 1-17, coeff. of variation 
averaged 56% in the four pairs). The average times between bouts 
for four pairs were 2.6, 3.5, 4.2, and 4.6 sec. (range 1.1-14.7, coeff. 
of variation averaged 56%). Usually the male held both front legs 
directed more or less anteriorly over the female’s head (solid lines in 
Figs. 1 and 2) during pauses between bouts. Bouts nearly always (88 
of 95 cases) began with the male raising both front legs simul- 
taneously (Fig. 1). Then one leg wound up and swung, and, as soon 
as it came to rest, the other leg wound up and swung. From then on 
tapping was nearly always strictly with alternate legs (205 of 207 
cases; in one case both legs hit simultaneously, and in the other the 
same leg hit twice in succession). The leg not being swung was held 
immobile while the other was lifted and swung. Average times 
between the downstrokes of taps were .41, .43, .44, and .49 sec. 
(range 0-1.5, coeff. of variation averaged 41%). Usually (40 of 50 
cases) the interval between the first two taps was shorter than that 
between the second and third. 
Twitching 
Twitching occurred between bouts of tapping when both of the 
male’s front legs had been immobile and apparently in contact with 
the female’s aristae. Twitching probably caused deflections of the 
aristae. To the naked eye the movements of the legs resembled 
rubbing, but the videotapes showed very rapid, brief (usually only 
1-2 frames), and variable movements. The legs moved dorsally, 
ventrally, or laterally to either side. Sometimes both front legs were 
twitched simultaneously, while in others only one was moved. More 
than a single twitch was performed in 9 of 20 pauses with twitches 
(maximum was 6). Individual males differed in their tendencies to 
twitch: three flies twitched at least once during 20 of 56 pauses, 
while the fourth did not twitch in any of 20 pauses (p < .05 with 
Chi-Squared Test). 
Rocking and scrabbling 
Scrabbling involved movements of the male’s body and all of his 
legs. The front and middle legs rubbed erratically on the female’s 
head and body, and his body moved short distances both laterally 
and forward and backward, also in an erratic pattern. 
