194 
Psyche 
[Vol. 91 
Assuming egg shape to approach that of a cylinder, we estimated 
volume of all chorionated eggs (EV) of 21 P.fasciata females using 
length and width as measured with an ocular micrometer. 
Results and Discussion 
When not actually copulating with a female, males rode in an 
amplexed position on the female dorso. Approach by a second male 
initiated a series of actions (Table 1). There were three components 
to these male interactions: orientation by the guarding male towards 
the intruder; stridulation by the guarding male; and an aggressive or 
nonaggressive action associated with contact by the intruder. 
Guarding males oriented towards intruders by rotating their whole 
body atop the female. Stridulation, audible to us at close range, 
involved scraping the beak back and forth across a file on the 
sternum. Often the guarding male began stridulating immediately 
upon approach by the intruder and occasionally continued even 
after the intruder’s departure. 
Contact by the intruder resulted in one of three behaviors by 
guarding males. Guarding males were either 1) passive (i.e., held 
their same position on the female whatever the intruder did) 
2) repositioned themselves so as to have their bodies always between 
the female and the intruding male, or 3) physically attacked the 
intruder. Attacks involved the use of the raptorial fore legs and were 
sometimes quite vigorous. We saw males grasp an intruder’s 
antenna for long periods and in one natural occurrence a guarder 
literally lifted his opponent off the substrate. No injuries were 
known to have resulted from this aggression, but individuals were 
seen with excised antennae and tarsae. 
Only one displacement of a guarding male was seen in the field 
and it was short-lived. After being maneuvered out of the amplexed 
position by an intruder, the original male immediately climbed on 
top of the pair and began shaking vigorously back and forth. This 
action eventually resulted in both males toppling to the ground, and 
then moving further from the female’s position. On two occasions in 
the laboratory similar separations of interactant males from females 
were observed. These apparently resulted from intruder males 
rocking vigorously while on top of paired males. 
In summary, mate guarding in P. fasciata is active and can be 
highly aggressive. It is also time-intensive. Typically, pairs already 
