Tarantulas are native residents of Southern California’s diverse ecosystems, prompting curiosity and concern due to their size. While they may seem incompatible with a modern city like Los Angeles, these arachnids are found throughout the county’s expansive wildlands. This article explores the specific species found in the region, clarifies their habitat, details the reasons for their seasonal appearances, and provides information on safe human interaction.
Confirming Their Presence and Range
Tarantulas are a natural part of the Los Angeles County fauna, though they are not typically encountered in the dense urban core. Their distribution is restricted to outlying natural areas, foothills, and canyons that support their burrowing lifestyle. Specific locations include the Santa Monica Mountains, Angeles National Forest, Griffith Park, and Topanga State Park.
These terrestrial spiders spend the vast majority of their lives underground in silk-lined burrows. They thrive in the dry, open grasslands and chaparral, only emerging under specific circumstances. While they inhabit the county, they are largely absent from built-up, paved environments.
Identifying the Local Species
The tarantulas found in Los Angeles belong to the genus Aphonopelma, which includes nearly all species native to North America. The most common species in Southern California is the California ebony tarantula (Aphonopelma eutylenum). The Mojave blonde tarantula (Aphonopelma iodius) is also present in the desert-facing fringes of the county. These spiders are characterized by robust, black-brown to dark brown coloring and a dense covering of hair across their bodies and legs.
Adult tarantulas can reach a body length of up to 2.75 inches, with a leg span extending between 4.5 and 5.5 inches. A significant difference exists in lifespan between the sexes. Females are long-lived, often surviving for 20 to 25 years by remaining in their burrows. Males typically live for 5 to 8 years, dedicating their final months to the search for a mate.
Annual Sightings and Behavior
Most people become aware of tarantulas due to a highly visible seasonal behavior known as the male “walkabout.” This is a mass emergence of mature males seeking females for reproduction, not a true migration. This activity typically begins in late summer and continues through early fall, often peaking around mid-October.
Male tarantulas leave the safety of their burrows and travel across open ground, sometimes covering several miles, following pheromones left by females. This quest for a mate is the only time these normally secretive, nocturnal spiders are frequently seen during the day, occasionally crossing hiking trails and roads. Females are largely sedentary and remain hidden in their established burrows. For the male, the mating period is often the final act of its life, as many die from exhaustion or are consumed by the female shortly after mating.
Safety and Coexistence
Despite their size, Los Angeles tarantulas are docile and pose a minimal threat to humans. They are not aggressive; their primary reaction to a threat is to flee or stand in a defensive posture. While they possess venom, it is mild and comparable to a common bee sting, causing localized pain but not posing a serious medical risk to people.
A more common defense mechanism is the use of urticating hairs. These are barbed, irritating bristles that the spider flicks from its abdomen toward a perceived threat. These hairs can cause skin irritation and, if they enter the eyes or respiratory system, more significant discomfort. The best course of action upon sighting one is to observe it from a distance and avoid touching or harassing the spider, allowing it to continue its journey.