Spider populations tend to peak in the later summer and early fall, and their webs seem to be everywhere right now. Some mornings, just walking out the door can bring a homeowner face to face with a giant web spun the previous evening by an industrious spider.
Anyone who has walked into a web by accident has probably encountered one of these, which seem to be especially abundant this year:
(Photo from Cobb County resident Janet A.)
The crablike spiny orb weaver (Gasteracantha elipsoides, sometimes also called the kite spider), shown above, usually exhibits some combination of white and/or yellow and black, with red, thorn-like "spines." It may look like something from outer space, but it actually is native from North Carolina to Florida, and west all the way to California.
These spiders tend to hang out along woodland edges. Like other spiders, the spiny orb weaver eats insects, so it is a great helper in the yard.
Reference: The Audubon Society Field Guide to North American Insects & Spiders, by Lorus and Margery Milne and Susan Rayfield. NY: Knopf, 1980.