1977 ] 
Ralston — Egg Guarding by Zelus 
105 
was a significant (p<0.01) difference between the guarding and 
non-guarding males in readiness to attack the model parasite. 
After hatching, the nymphs appeared to stay very close to the 
eggs and guardian male for several days (a maximum of seven days 
in one case). In one instance in the field I watched a male capture 
a small insect about 15-30 cm from the egg masses where the 
nymphs were gathered. He promptly returned to the nymphs with 
the insect and the nymphs fed on it. I attempted unsuccessfully to 
repeat this observation in the lab with a few males, several nymphs, 
and tiny insects. Dr. William Eberhard (personal communication) 
reports seeing recently (February 1977) a guarding male holding a 
prey with a cluster of nymphs gathered around apparently sucking 
the prey. 
Rates of Parasitism 
On January 28, I finished marking 22 males guarding egg masses 
(control group) as well as the sites of the egg masses. The males 
were marked with white airplane dope on the anterior dorsal sur- 
face of the thorax. This did not appear to interfere with their 
normal functioning. I also removed 22 males from the masses they 
were guarding and marked the sites of the egg masses (experi- 
mental group). Each tree in which I made the study contained 
both control and experimental groups distributed roughly at ran- 
dom. However, if different groups of egg masses were very close 
together, I labeled them all control or all experimental so that the 
presence of a nearby male would not affect parasitism of unguarded 
eggs. The purpose of this experiment was to see if the presence of 
the guarding male affected the rate of parasitism of the eggs. 
On February 20, I collected 57 egg masses from the marked sites 
with guarding males and 63 egg masses which had been left un- 
guarded. Of the 57 guarded egg masses, 12 (21%) had been para- 
sitized (distinguished by eggs with unbroken seals and tiny exit holes 
near their attached ends); whereas 35 (55%) of the 63 unguarded 
egg masses had been parasitized. A chi-square test shows that the 
difference between the rate of parasitism of unguarded and guarded 
egg masses is statistically significant (p<0.01). Five tiny wasp 
parasites of the genus Telenomus (Scelionidae) hatched from one 
egg mass in the experimental group soon after it was collected. 
