The Gift of Trapdoor Spiders

Not every spider builds an aerial masterpiece like Charlotte in “Charlotte’s Web.” Many spiders stay close to the ground and some, like tarantulas and trapdoor spiders, live underground.

Trapdoor spiders are found worldwide, from Africa, Australia, and China, to North and South America. On our hillside in Los Angeles, we are fortunate to have a colony of California trapdoor spiders (Bothriocyrtum califonicum) a native Pacific Coast species. The heavy adobe soil poses a gardening challenge, but creates prime real estate for burrowing spiders. The native clay is structurally strong, while the hillside slope allows rapid runoff of water. This combination has prevented humans from planting exotic landscaping, which in turn has allowed these trapdoor spiders to thrive.

This photo shows the first trapdoor home I discovered in our yard. Though the spider camouflages its door with dirt and debris, the large size of this protective door allowed me to spot the distinctive “D”-shaped covering.

The back edge of the “D” creates the web-constructed hinge, which allows the spider to open it’s door when it detects prey on its doorstep. The spider lifts up the door, grabs the cricket, spider or other unwary arthropod, and pulls in down into its tunnel. Layers of webbing make the eight-inch deep tunnel a cozy home for the California trapdoor spider.

The door also provides protection. From inside, the trapdoor spider can hold the door tightly closed. The precision of the door’s closure makes it almost impossible to open without damaging the door. This was the first time I was able to open this door. Unfortunately, it was because the large adult female spider must have passed away. Female trapdoor spiders are believed to live up to 12 years. I have known this spider to reside in this large tunnel for 13 years.

Trapdoor females are homebodies, preferring to spend their lives in one location. Males may wander past her door, but the female spends her life quietly underground. She is also a good mother, raising her spiderlings in her web-lined tunnel. She protects them and provides them with food for a year until they are large enough to strike out on their own.

All around the hillside matriarch there are tunnels and doors of younger trapdoor spiders. Some are eaten by other predators and their tiny doors have broken off to reveal the narrow tunnel without an owner.

Others are approaching the size of their mother’s tunnel.

Spiders are ancient creatures. The fossil record shows evidence of spiders 350 million years ago, long before dinosaurs or the first mammals. How long has this colony of trapdoor spiders lived on this hillside? Probably, long before humans lived in this valley.

The experts don’t believe the shy and secretive trapdoor spider lives in the built-up city of Los Angeles anymore. But in little fragments of native habitat, these ancient creatures survive. I am in awe of this colony of spiders. I am careful not to plant too many plants on the bare earth they prefer. I knock on human neighbor’s doors when their overwatering threatens to flood the spiders. I try to preserve their plot of hillside so their colony can continue on long after I am gone.

Native wildlife is a treasure, a gift. Big or small, plant or animal, this year make it your mission to preserve and protect.

For great PICTURES of trapdoor spiders, including a mother with her young, visit

www.dbc.uci.edu/~pjbryant/biodiv/spiders/Bothriocyrtum%20californicum.htm