By summer’s end, huge female garden spiders seem to appear everywhere, building 2-foot-wide webs in gardens, fields and parks throughout coastal Southern California. These stunning spiders with inch-long bodies hatch the previous fall but remain hidden, building small, inconspicuous webs in low vegetation until they reach maturity in late summer. By that time, quarter-inch-long males are on the prowl for females, lurking at the perimeter of the females’ webs until they are receptive to mating. Within moments of mating, a male goes into death throes so his body can create a “plug” that prevents the female from mating again. The female soon spins one to three dense brown cocoons that each hold up to 1,400 eggs, which she guards unless cold winter weather kills her.
The web is distinctive because the female builds a silvery zigzag pattern, called a stabilimentum, in the center. It’s thought that this structure serves as a warning flag so birds don’t fly into the web and ruin the female’s hard work.
This spider’s egg-shaped abdomen has striking yellow markings on a black background; the black legs have red or yellow bases.