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Psyche 
[Vol. 92 
way for a male to prevent a receptive female from mounting and 
feeding upon a displaying rival (and thus copulating) is for the male 
to do the mounting and feeding himself. When a receptive female 
responds to a rival’s full wing raising display, it is too late for a male 
to effectively court the female. At this point the only way to preserve 
the opportunity to direct effective courtship to the female is to first 
disrupt the ongoing copulation sequence involving the rival male. In 
a small population of cockroaches of these species, only one or 
several receptive females will be present at any given time. A male 
performing pseudofemale behavior prevents an imminent loss of a 
scarce resource, i.e., the receptive female. The receptive female con- 
sequently remains available to respond to subsequent courtship by 
the pseudofemale performer. 
A second aspect of aggressive pseudofemale behavior is related to 
the fact that a courting male is quite vulnerable to attack when 
giving a full wing raising display. A male employing pseudofemale 
mounting and feeding behavior is able to “lure” the displaying male 
into a still more vulnerable position and then unleash a sudden 
attack at the very moment the displaying rival is attempting copula- 
tion. The result is that the displaying male is driven away and pre- 
vented, at least for the moment, from copulating. Such an encounter 
might also exert a negative influence upon the propensity for subse- 
quent courtship by the victim of the pseudofemale attack. To sum 
up, the pseudofemale actor engages in behavior that simultaneously 
increases his fitness and decreases that of his competitor. 
A male may engage in pseudofemale behavior as a prelude to an 
attack or he may attack directly. There appears to be a gradation of 
responses between these two alternative behavior patterns. Which is 
chosen may depend upon (a) the level of aggressive tendencies in the 
attacking male, (b) the temporal proximity to the onset of female 
mounting, and (c) the relative position of the two males. 
In the species reported on here, female sex pheromones are 
interspecifically effective in releasing male courtship behavior 
(Barth 1970, Wendelken 1976). Interspecific differences in male sex 
pheromones play a vital role in reproductive isolation among these 
species. With the exception of the combination B. parabolicus X B. 
discoidalis, females either refuse or are reluctant to mount and feed 
in response to the displays of heterospecific males (Wendelken 1976). 
These findings are generally consistent with the results of interspe- 
