Like all spiders, black-and-yellow argiopes are carnivorous. They spin an orb web to capture small flying insects such as aphids, flies, grasshoppers, and Hymenoptera (wasps and bees). A female can take prey up to 47mm in diameter, up to 200% of her own size (Nyffeler et al. 1987)
The web can be up to two feet across. The spider hangs, head down, in the center of their web while waiting for prey. Often, she holds her legs together in pairs so that it looks as if there are only four of them. Sometimes the spider may hide in a nearby leaf or grass stem, connected to the center of the web by a nonsticky thread which quivers when prey lands in the web.
Web construction is complicated. To start the web, Argiope firmly grasps a substrate like a grass stem or window frame. She lifts her abdomen and emits several strands of silk from her spinnerets that merge into one thread. The free end of the thread drifts until it touches something far away, like a stem or a flower stalk. She then creates bridge lines, and other scaffolding to help her build the framework of the web. She builds a hub with threads radiating from it like a spokes of a wheel. She switches to sticky silk for the threads spiraling around this hub that will actually catch her prey. It may take a few hours to complete the web, then she eats the temporary scaffolding and the center hub. Argiope spiders often add stabilimenta, or heavy zig-zagging portions, in their webs. A stabilimentum may or may not aid prey capture (see below). The entire web is usually eaten and then rebuilt each night, often in the same place. (Dewey, 1993; Faulkner, 1999; Lyon, 1995; Milne and Milne, 1980; Nyffeler, Dean, and Sterling, 1987; Zschokke, 2006)