300 
Psyche 
[Vol. 89 
Approximately 12-14 days after mating, a circular, flattened, 
creamy white egg sac was produced by the female. The size of the 
sac ranged from 1.27 to 2.54 cm in diameter, and was from 3.18 to 
6.35 mm thick. A network of silk was deposited on the underside of 
a flat surface, such as a leaf or plastic housing container lid. The 
eggs (each ca. 1 .5 mm dia.) were deposited on this base, and covered 
with another layer of silk. After the egg sac was sealed around the 
edges and removed from the foundation, the female carried it with 
her pedipalps underneath her body during the incubation period. 
The female usually did not eat during this time. Infertile egg sacs 
were sometimes dropped or eaten by the female. A large number of 
infertile egg sacs (54% of those produced in the laboratory) were 
constructed by the reared spiders. This might be expected due to the 
artificially imposed mating schedule. An average of 2.16 fertile egg 
sacs were produced per female, with five the highest number. An 
average of 163 eggs were laid in each fertile egg mass (n = 13 egg 
masses, SD = 28.97) constructed by the experimental spiders. 
Bonnet (1932) reported 207 spiderlings emerging from the one egg 
mass from a female he had raised after obtaining it as an immature 
spider on bananas shipped from Africa. Sekiguchi (1944a) obtained 
188-436 eggs/ mass. In field observations we have found as many as 
400 spiderlings in one egg sac. This may indicate that a high degree 
of variability in egg mass size is common. No data were taken on the 
numbers in consecutive egg sacs. 
Peck and Whitcomb (1970) included a discussion of the postem- 
bryonic stages and reviewed the terminology used in the literature to 
describe them. The definitions used in the present study follow 
theirs and are given below to avoid confusion. The first postembryo 
is defined as being that stage after the chorion of the egg had been 
shed from most of the embryo, but remained as a crumpled mass at 
the posterior end. The second postembryo is defined as being that 
stage after the vitelline membrane had been shed and the embryo 
was completely free, with legs able to move. After the first molt the 
spiderling was considered to be a first instar. This molt occurred 
inside the egg sac. Bonnet (1932) and Sekiguchi (1944a) considered 
the emerged spiderlings to be second instars. 
Several egg sacs were removed from CCh-anesthetized female 
spiders, opened, and placed in covered petri dishes for observation. 
The egg stage lasted from 8-14 days (n = 6 egg masses). Eclosion 
