1985] 
Wendelken & Barth — Pseudofemale behavior 
499 
Discussion 
The conditions under which observations were made in the labor- 
atory appear to approximate rather well important conditions 
found in some natural populations. Gautier (1974) studied a high 
density population of Blaberus colosseus in a Trinidad cave and 
found that the cockroaches “live in groups including males, females 
at different phases of their reproductive cycle and older nymphs. 
These males are not territorial, only very few are observed away 
from the group.” Sexually receptive females were found to travel as 
much as several meters in a day and this caused modifications in the 
distribution of males. In cockroaches (e.g., Blaberus spp.) with a 
volatile female sex pheromone, the female sex pheromone acts to 
attract males but is effective over a distance of a few feet at most 
(Barth 1968a). In the high density population studied by Gautier 
(1974), clearly a number of males would come into contact with a 
sexually receptive female. Gautier (1978) studied another high den- 
sity cave population of B. colosseus in Trinidad. He found that 
“males are not territorial on sites” which they occupy and that the 
interindividual relationships of males are of short duration and low 
intensity. And, significantly, “the presence of a female changes 
male/ male relationships quickly and profoundly by stimulating 
aggressiveness” in the males. Gautier (1978) also observed a number 
of cases in which two males were simultaneously in contact with a 
single female. He concluded that his field observations confirmed 
his finding in the laboratory that the presence of a female releases 
aggressive behavior between males. 
Sexual selection may lead to the evolution of intense male-male 
aggression. This appears to have been the case in the genera Blabe- 
rus, Archimandrita, and Byrsotria (Wendelken 1976). In the species 
reported on here, direct confrontations take place between compet- 
ing males in the presence of a female. Males aggressively interfere 
with the courtship of other males, including foiling the female 
mounting and feeding sequence. It is in this context that we find 
pseudofemale mounting and feeding with subsequent biting of the 
displaying male. Aggressive pseudofemale behavior appears to func- 
tion as one of an array of methods by which a male can discourage 
the copulation of a receptive female with one of his rivals and thus 
increase his own chances of copulation. If a male mounts a display- 
ing rival, the female is precluded from doing so. In other words, one 
