138 
Psyche 
[June-September 
In the present study we asessed seasonal variation in spiderling 
emergence through long term field observation of egg sacs laid 
throughout the restricted oviposition period. Seasonal variation in 
causes of failure to emerge, the number of eggs per clutch, individ¬ 
ual egg weight, and the total egg clutch weight were also assessed. 
Methods 
Study Area 
The study area is located 20 km south of New Orleans, La. at the 
F. Edward Hebert Center of Tulane University. Observations were 
made within a bottomland hardwood forest cut by drainage ditches 
and dirt roads. Refer to Christenson and Wenzl (manuscript sub¬ 
mitted) for a more detailed description of the study area. Observa¬ 
tions were made during the 1975-1978 seasons. 
Procedures 
To determine if there was seasonal variation in spiderling emer¬ 
gence, we compared spring emergence data from egg sacs formed in 
early, mid, and late season. Each trimester was about six weeks in 
length. Throughout the egg laying season a set of pathways we had 
established in the cleared and forested areas were traversed system¬ 
atically at least once a week in search of egg clutches. The only 
criterion for selection was that the egg sac be within 2.5 m of the 
ground. The approximate date the egg sac was formed was deter¬ 
mined by the date of discovery, whether the eggs had hatched, and 
silk color, since the silk turned from white to gold within a week of 
being spun. Hatching was determined by gentle palpation of the egg 
sac. A total of 439 egg sacs were observed throughout the winters of 
1975-1978; these accounted for about 60% of the total in the 3 ha 
study area. The decrease in foliage in winter exposed the egg sacs 
and facilitated a near total count. Each sac was tagged by placing 
tape on a nearby twig, and inspected periodically until spiderling 
emergence, beginning in March. We noted changes in egg sac struc¬ 
ture and position, presence of fungus or predators, general condi¬ 
tion of the eggs, hatching, and emergence from the sac. The 1975 
and 1976 sacs were checked twice a week, the 1977 sacs once a week, 
and 1978 sacs weekly through January and monthly thereafter. 
Data from 1978, therefore, are not as complete as those from the 
previous years. 
