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California Trapdoor Spider (Bothriocyrtum californicum)

Detailing the physical features, habits, territorial reach and other identifying qualities of the California Trapdoor Spider

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Image Credit: Patty S. from CA
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Image Credit: John E. W. from San Diego, CA
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An arachnid version of the Jack-in-the-Box toy, California Trapdoor Spiders are not at all amusing to the prey they startle.

Updated: 01/26/2021; Authored By Staff Writer; Content ©www.InsectIdentification.org
California Trapdoor Spiders are native to Southern California. In many ways, they resemble smaller versions of tarantulas, but with shiny, hairless bodies. The whole spider is black except for the rusty brown abdomen. The large, round cephalothorax has a deep dimple in the center of it. The chelicerae (jaws) have spines on them that help this species with digging underground burrows. 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, sometimes sooner rather than later thanks to heavy spring rains.

These burrows can be 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 gets pulled down into the trap and restrained in the burrow by both the spider's body as well as silk-covered walls inside the burrow. The prey is consumed below the door, leaving no warning above for future passersby.

Known Diet of the California-Trapdoor-Spider

spiders, insects, millipedes

General Characteristics
Capability, Shape, Texture/Pattern, Benefits, Dangers
Rounded insect body icon


Taxonomic Hierarchy
Species Breakdown
Kingdom: Animalia
  Phylum: Arthropoda
    Class: Arachnida
      Order: Araneae
        Family: Ctenizidae
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          Genus: Bothriocyrtum
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            Species: californicum
Identifying Information
Size, Colors, Features
Scientific Name: Bothriocyrtum californicum
Other Name(s): Trapdoor Spider
Category: Spider
Size (Adult; Length): 18mm to 33mm (0.70" to 1.29")
Colorwheel Graphic Colors: black; brown; yellow
Descriptors: two-toned, pop-up, trapdoor, underground, ambush

Relative Size Comparison
Typical Size Between 18mm (0.7in) and 33mm (1.3in)
Lo: 18mm
Md: 25.5mm
Hi: 33mm
Territorial Map*
U.S., Canada, and Mexico
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Prince Edward Is.  
* MAP NOTES: The territorial heat map above showcases (in red) the states and territories of North America where the California Trapdoor Spider may be found (but is not limited to). This sort of data is useful when attempting to see concentrations of particular species across the continent as well as revealing possible migratory patterns over a species' given lifespan. Some insects are naturally confined by environment, weather, mating habits, food resources and the like while others see widespread expansion across most, or all, of North America. States/Territories shown above are a general indicator of areas inhabited by the California Trapdoor Spider. Insects generally go where they please, typically driven by diet, environmental changes, and / or mating habits.


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