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Psyche 
[September 
of the male was extended somewhat so that the intersegmental 
membranes between abdominal tergites one and two and seven and 
eight were exposed. The male then displayed the lateral jerking or 
vibration movement described by Roth and Willis (1954). This 
movement resembled the lateral jerking which often precedes aggres- 
sive encounters in Periplaneta (Barth, 1968a), except that each 
burst of movement usually consisted of five to ten small amplitude 
side to side swings of the body rather than two or three, as in Peri- 
planeta. The movement seemed to result from alternate flexion and 
extension of the legs (particularly the femur-tibial joint) of the two 
sides during which the tarsi remained firmly planted on the sub- 
stratum. These bursts of lateral vibration were generally performed 
two or three times in succession, with brief rest periods of from one 
to three or four seconds between them. Then after a long rest period 
of from 15 to 30 seconds, the series of bursts was repeated, each 
burst lasting about a second. During lateral vibration the abdomen 
was often extended somewhat more, so that the intersegmental 
membrane between tergites six and seven also became visible. It is 
worth noting that not all males expose the intersegmental membranes 
during vibration. Membrane exposure may be related to the level 
of sexual motivation in the particular individual concerned. 
After several sets of vibration bursts, the female mounted the 
male actively and performed feeding movements for nearly a minute 
on the surface of the first two abdominal tergites. In this particular 
sequence, the female mounted from the side and, though the male 
made feeble attempts to twist around underneath the female, no 
genital connection was achieved. While the female was mounting, 
the male extended his abdomen considerably and pressed it against 
the substratum. The phallomeres were protruded partially from 
time to time. During mounting and copulation attempts, the an- 
tennae of both pair members oscillated vigorously. The female 
finally slipped off and the two faced each other with heads touching 
and antennae waving slowly for about two minutes. The male held 
his abdomen off the substratum and showed bursts of lateral vibra- 
tion every few seconds. Four times during this period the female 
responded to the male’s vibration with lateral vibration bursts of 
her own. The genital opening of the female gaped widely, which 
from a number of observations appears to be characteristic of recep- 
tive females. The male then ceased vibrating, moved back a few 
steps, and turned 90°, so that he was oriented laterally to the female. 
The female attempted to mount but was knocked off by a third indi- 
vidual passing by. The male vibrated again and turned another 90°, 
