Their burrows can up more than 7 or 8 inches deep and serve as both a home and a trap. The top of the burrow opening is covered with a silk door that is hinged. As the years pass, spiders add more silk webbing to their doors. They may also collect debris and loose leaf litter, helping to camouflage its existence. Burrows are usually built into hillsides or cliff-faces, often facing direct sunlight for ambient warmth and usually near vegetation that is likely to attract insects.
Under this door, the spider waits and, when it senses oncoming prey, it quickly lunges out of its burrow and catches the prey item. Once caught, the prey is restrained in the burrow by both the spider's body as well as the silk walls inside the burrow. The prey is consumed inside the tunnel, out of sight.
As is the case with most spiders, the female California Trapdoor spider is larger than the male. Males search for females during the winter months. Females lay their fertilized eggs at the bottom of the burrow. Once spiderlings hatch, they leave the burrow, usually thanks to the prompting of a heavy spring rain.