24 
Psyche 
[March 
frequencies of these behaviors are scarce. Approximately 20 argio- 
pids were observed to reballoon during the course of the study, 
some as many as six times with the majority (90%) of these observed 
reballooning bouts occurring when the spiderlings were in close 
proximity to the egg sac. It is possible that a minimum time or 
distance requirement must be achieved before the spiderling has 
satisfied a “ballooning drive.” It might also reflect investigator 
error since spiderlings which drop into dense vegetation are diffi- 
cult to detect and the probability of finding individuals must de- 
crease with distance from the egg sac (with decreased density of 
spiderlings). Nevertheless, multiple ballooning bouts probably func- 
tion to increase emigration from a given area (which would tend to 
lessen competition for food, web sites or other resources if such 
resources are in short supply). Since Argiope spp. actively select 
web sites (Enders, 1972, 1973), it is probable that areas judged un- 
suitable by the spiderlings can be quickly and easily abandoned via 
reballooning. This finding is consistent with the predictions of 
Doyle’s (1975) habitat selection model. Organisms which encounter 
coarse-grained (patchy) environments, as Argiope do, can improve 
fitness by selecting habitat types yielding highest survivorship. Riech- 
ert (1973) demonstrated that a desert agelenid spider, Agelenopsis 
aperta (Gertsch) improved the quality of its web sites by successive 
relocation in better web sites. A. aperta walked rather than bal- 
looned to new web sites, however. Riechert and Tracy (1975) pro- 
duced a model of reproductive success that demonstrates a thirteen 
fold advantage in fecundity of spiders living in good versus poor 
web sites. Habitat selection and differential survival of Argiope 
spp. is an area worthy of additional research. 
One or more days may elapse after the spiderling locates a web 
site before it actually builds a web there. This is based on two sets 
of observations. First, spiderlings discovered in the field without 
webs and checked later the same day had not built webs (N = 5). 
Only spiderlings found early in the morning and thus not recently 
dispersed are considered here. Two of these individuals built webs 
one day later; one built two days later. Second, even during the 
height of Argiope trifasciata aerial dispersal (mid-May) few spider- 
lings were observed to have webs. Possibly the spiderlings were 
adjusting from a colonial, passive existence to one of active preda- 
tion. Whatever the reason(s), considerable mortality is suffered 
during this period (Tolbert, 1976). Spiderlings would certainly be 
