Insect Identification
Insect Identification

California Trapdoor Spider - (Bothriocyrtum californicum)

Authored By Staff Writer | Last Updated: 1/7/2014

The arachnid version of the Jack-in-the-Box, California Trapdoor Spiders are not amusing to the prey they startle.

California Trapdoor Spiders are native to Southern California. In many ways, they resemble smaller versions of tarantulas, but with shiny, hairless bodies. Their chelicerae (jaws) have spines on them, which aids this species in digging their burrows underground.

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.

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Category: Spider
Common name: California Trapdoor Spider
Scientific Name: Bothriocyrtum californicum
Other Names: Trapdoor Spider

  Kingdom: Animalia
   Phylum: Arthropoda
    Class: Arachnida
     Order: Araneae
      Family: Ctenizidae
       Genus: Bothriocyrtum
        Species: californicum

Adult Size (Length): 18mm to 33mm (0.71in to 1.30in)

Identifying Colors: black; brown; yellow

Additional Descriptors: two-toned, pop-up, trapdoor, underground, ambush

North American Reach (Though Not Limited To*): California

* Keep in mind that insect reach is not governed by lines on a map and therefore may appear in areas/regions/states beyond those listed above.