1971] 
W endelken & Barth — Parcoblatta 
325 
volved in eliciting these responses. The males of this species are 
small and no more than three were ever employed ; in the mating 
chamber, contact between males was infrequent in this situation. 
Probably because of the low density of males, neither homosexual 
or pseudofemale behavior was observed in the mating chambers al- 
though one instance of a male mounting a displaying male was 
observed in the more crowded breeding culture. That males have 
a considerable ability to orient to a pheromone source was shown 
in several instances during the observation periods when a male 
precisely followed the “trail” of a female that had previously 
decamped. 
Turning and backing were not released during the filter paper 
tests nor in the behavior observations except when a male was very 
close to a female. Turning and backing in the majority of these 
cases were released by contact chemoreception and/or tactile stimuli 
when the male’s antennae contacted a female. However, in a signifi- 
cant number of cases the release of these activities was triggered 
solely by the apparently intense concentration of sex pheromone 
immediately surrounding the female. 
Tactile stimuli are necessary for the release of copulatory thrusts 
and phallomere extension. 'Copulatory thrusts begin when the mount- 
ing female’s mouthparts have progressed about two-thirds of the way 
forward over the male’s abdominal tergites. Whether phallomere 
extension occurs at this point or not until the female reaches the 
region of the first tergite is uncertain. 
Predominance of the female sex pheromone in the release of male 
courtship behavior has also been reported for the distantly related 
species, Periplaneta americana (Blattinae) (Barth, 1970; Simon and 
Barth, in prep.). As mentioned above, both species show wing 
raising in the absence of tactile stimuli and during forward loco- 
motion. However, turning and backing (in addition to the full 
wing raising display) only rarely occur in the absence of tactile 
stimulation in P. americana (Barth, 1970) but are not infrequently 
observed in P. fulvescens. In this respect, the female sex pheromone 
plays a more prominent role in courtship behavior in P. fulvescens 
than in P. americana. Backing in P. americana (as well as in 
four other species of Periplaneta and also Blatta orientalist often 
occurs without any tactile stimuli in addition to those which release 
wing raising with turning (Simon and Barth, in prep.). This is 
also true of P. fulvescens in those cases in which tactile stimuli 
release the wing raising display. P. americana males differ from 
