At close to 20 mm in length and prominently marked with black and yellow bands on a silvery white background ("trifasciata" means three banded), this beautiful spider seems to be less common than the closely related Black and Yellow Argiope (Argiope aurantia). The female in the following four images was encountered in a sunny, dry field about a kilometer west of town.
These photos of what is a probably a male Banded Argiope were taken about a month earlier. It's unfortunate that I haven't been able to obtain a picture of a male and female spider next to one another, because something that photos can't convey is scale. Sexual dimorphism among spiders can be extreme, and at a length somewhere between 5 to 10 mm this male would be dwarfed by the much more robust female.