how long does it take for the banded argiope eggs to hatch?

Answer 1

What an INCREDIBLE spider!! Thanks for the search. Doesn't seem to say exactly how long, but will keep looking -- for now, this from Wikipedia:

"The male spider is much smaller than the female, and unassumingly marked. When it is time to mate, he spins a companion web alongside the female's. After mating, the female lays her eggs, placing her egg sac into the web. The sac contains between 400 and 1,400 eggs. These eggs hatch in autumn, but the spiderlings overwinter in the sac and emerge during the spring. The egg sac is composed of multiple layers of silk and designed to protect its contents from damage; however, many species of insects have been observed to parasitise the egg sacs."

Okay, more info, from Cornell University Entomology Dept. -- leads me to believe there is not a definite time to hatching, and you may be fooled because the spiderlings over-winter INSIDE the egg sac! Cool!

"You are most likely to see Argiope in the late summer and early autumn. This is when the females mature, becoming very large as they yolk up their eggs. The females will construct one or more egg sacs in autumn. The egg sacs will be attached to vegetation near the website and can contain hundreds of eggs. The young hatch in autumn but remain inside the eggsac over winter. Spiderlings emerge from the eggsacs in the spring and build small webs deep in grass and other vegetation throughout the summer. As the spiders grow in size they tend build larger webs higher in the vegetation and thus more noticeable. Once mature, males stop building webs altogether and instead search for females with which to mate. Females will continue to build webs as adults."