Everything to Know About Spiders in Southern California
Spiders are among the most common pests in Southern California. While they inspire fear in many homeowners, most species are harmless and even beneficial since they help control flies, ants, mosquitoes, and other insects. Still, when they move indoors, spiders often cause stress with their webs and, in rare cases, can pose health risks if venomous species are present. This guide covers everything you need to know about spider biology, what attracts them inside, what they eat, venom levels, and prevention tips. Along the way, we’ll highlight additional resources on specific species and infestations in our area.
Everything to Know About Spiders
The Biology of Spiders
Spiders belong to the class Arachnida, which also includes ticks, mites, and scorpions. Unlike insects, they have eight legs and two body parts: the cephalothorax and abdomen. Specialized silk glands allow them to spin webs used for hunting, egg sacs, or shelter.
The life cycle begins with eggs inside silken sacs. Spiderlings disperse and grow into adults, with lifespans ranging from a single year to decades for tarantulas. We go deeper into lifespans in our article on how long spiders live.
Different species also rely on different hunting strategies. Web-builders like orb weavers catch prey in silk traps, while hunting spiders such as wolf spiders and jumping spiders pursue insects directly. For a closer look at species in our region, we’ve detailed common California spider species.
What Attracts Spiders Into Homes
The main reason spiders move indoors is food. If you have ants, flies, or mosquitoes inside, spiders are likely to follow. Dark, undisturbed areas like basements, attics, and closets are also attractive because they provide safe shelter. Seasonal changes matter too: in the fall, males wander indoors looking for mates, which is why sightings suddenly increase. We explain this trend further in our guide to spider infestations in Southern California.
What Do Spiders Eat?
Spiders are carnivores, and their diets make them natural pest controllers. Still, when infestations grow indoors, the benefits quickly become a nuisance.
What Spiders Commonly Eat:
Flies
Mosquitoes
Ants
Moths
Beetles
Roaches
Wasps
Other spiders (depending on the species)
Some species rely on intricate webs to trap flying insects, while wolf spiders and jumping spiders hunt prey directly. Indoors, spiders often target household pests such as roaches and ants. We also explore comparisons between ticks and spiders, which often share habitats but play very different roles.
Spider Venom: Harmless vs. Dangerous Species
Nearly all spiders have venom, but its potency varies. In most cases, it only affects insect prey, and bites to humans result in minor irritation. However, some Southern California species are considered medically significant and require caution.
Levels of Spider Venom:
Mild/Harmless
Example Species: House spiders, orb weavers, cellar spiders
Impact on Humans: Bites may cause slight irritation or go unnoticed. Not medically significant.
Moderate
Example Species: Wolf spiders, jumping spiders
Impact on Humans: Bites may cause pain, redness, and localized swelling. Usually not serious.
Dangerous
Example Species: Black widow, brown recluse
Impact on Humans: Bites can cause severe reactions like cramping, tissue damage, or systemic illness. Medical attention may be required.
Black widows and brown recluse spiders are the most concerning in Southern California. Black widow venom can cause severe pain and muscle cramping, while recluse bites may lead to tissue damage if untreated. For more details, see the guide on dangerous spiders in California and the resource explaining whether brown spiders are poisonous. To debunk common myths, the article on daddy longlegs spiders clarifies the truth about their venom.
Prevention and Control Tips for Spiders
Reducing spider activity means addressing the insects they feed on, limiting shelter, and making homes less inviting.
Spider Prevention and Control Tips:
Seal cracks and crevices around doors, windows, and foundations
Install or repair window and door screens
Reduce clutter in basements, attics, and garages
Store firewood away from the home and off the ground
Trim shrubs, trees, and vegetation that touch the house
Regularly vacuum webs and corners indoors
Address insect problems that attract spiders
Use yellow-toned exterior lights to reduce insect activity around the home
Schedule professional spider inspections and treatments for long-term control
For additional solutions, we share practical repellents in our guide to indoor spider control.
Living With and Without Spiders
Spiders are essential outdoors, keeping insect populations in balance. Indoors, however, they create stress and sometimes health concerns. By understanding spider biology, food sources, and venom, Southern California homeowners can take proactive steps to reduce encounters.
When venomous species are involved, or infestations grow too large, professional pest control remains the safest and most effective option.
Spider Control in Southern California
Spiders may be fascinating creatures, but they don’t belong inside your home. While most are harmless, their presence can create fear and health concerns. At ProCraft Pest Control, we provide expert spider control services in Southern California, targeting both spiders and the pests they feed on. From everyday cobweb spiders to venomous black widows, our team has the expertise to keep your home safe and comfortable. Contact us today to schedule an inspection and take the first step toward a spider-free home.
I’ve worked in pest control since I was 20 and founded ProCraft in 2009. After decades in the field, I’ve learned spiders are best managed through prevention and precision—not panic. My goal is to keep homes safe and spider-free with proven control methods that last.
