1968] 
Barth — Behavior of Eurycotis 
277 
so that his abdominal tip was near the female’s head. This turning 
or pivoting of the male between series of lateral vibration bursts 
appears to be quite characteristic of this species. At this point, the 
female mounted again and fed vigorously in the vicinity of the first 
two abdominal tergites, though occasionally her mouthparts wandered 
as far forward as the prothorax. The abdomen of the male was 
markedly extended and depressed against the substratum^ and the 
phallomeres were protruded rhythmically. After another minute 
during which the female twice slipped off to the side and remounted, 
the union was accomplished, the female slipping off to one side and 
swinging around 180°. Internal twisting of the male’s genitalia 
must have occurred during the turning movement, as there was no 
sign of abdominal twisting during or after the assumption of the 
opposed position. The female’s genital opening gaped so widely 
during copulation that the whole tip of the male’s abdomen appears 
to be inserted, as is shown in Plate 3 of Roth and Willis (1954). 
2. General observations on mating behavior in E. floridana 
Surprisingly enough, the female clearly seems to be the initiator 
of courtship behavior in this species. She was the initiator in virtually 
all the mating sequences observed. In the mating behavior observa- 
tion chamber experiments, a number of females invariably rushed 
into the male side of the chamber as soon as the partition was 
removed. By contrast, the males usually remained motionless, though 
sometimes a few slowly wandered into the female side of the chamber. 
Even males showing lateral vibration and therefore presumably 
sexually motivated, made no effort to seek out females. Rather, they 
remained stationary, letting the females approach and mount before 
attempting copulation. Females tended to mount males quite indis- 
criminately whether the latter were showing the vibration movement 
or not. Generally, non-vibrating males remained entirely passive 
when mounted by a female, in which case the female usually departed 
after a minute or two of feeding^ but occasionally they responded 
aggressively to mounting attempts by jerking the abdomen upward 
and/or kicking back with the metathoracic legs, or more rarely, they 
responded by running out from under a mounting female. In the 
latter case, the female often chased the escaping male for a short 
distance, attempting to remount. Generally, only those males which 
have shown the lateral vibration movement attempt to copulate with 
a mounting female. Only a single case was observed in which a 
male mounted by a female attempted copulation without having 
previously shown lateral vibration. Occasionally a female may 
