Spiders By: Mike Kobus

"The itsy-bitsy spider went up the waterspout,
Down came the rain and washed the spider out.
Out came the sun and dried up all the rain,
And the itsy-bitsy spider went up the spout again."

In Northern California, recent years have brought substantial rainfall, refilling major reservoirs and even achieving near-full capacity in some areas. This improved water situation has shifted local ecosystems, impacting many species, including spiders. While spiders typically thrive in warm, dry conditions, the recent moisture has encouraged lush vegetation growth, indirectly supporting spider populations as more insect prey becomes available.

Although spider activity tends to peak in late summer and early fall, residents may encounter them year-round, especially indoors during colder months. Spiders generally prefer outdoor environments but sometimes find their way inside, often by accident. For example, a spider may hitchhike on firewood. When you bring a log inside and set it near the fireplace, the warmth can awaken any hidden spiders. To avoid surprises, inspect each piece of firewood carefully—and wear gloves—before bringing it into your home.

Brown Recluse Spiders

Despite popular belief, brown recluse spiders are not native to California. While they may occasionally arrive via transported goods, California's climate typically prevents them from establishing permanent populations. They prefer warmer, humid climates, like those found in southeastern states.

Identifying Common Local Spiders

Spiders are arthropods with two main body segments (the cephalothorax and abdomen), eight legs, and six or eight eyes. In contrast, insects have three body segments (head, thorax, and abdomen), six legs, and two compound eyes.

In our area, two common spiders are the wolf spider and the black widow.

• Wolf Spiders: Usually dark brown and hairy with a sturdy body, wolf spiders look intimidating and are fast-moving. They don't spin webs to catch prey, though they may leave draglines, or “safety lines,” behind as they move. Their strong mouthparts can inject venom, but bites are generally less painful than bee stings.

• Black Widow Spiders: The female black widow is glossy black with a red hourglass marking on the underside of her abdomen. She tends to be shy and usually hides in her web’s corners, although she may be more aggressive if guarding an egg sac. Black widow webs are irregular, sticky, and remarkably strong. A bite from a black widow releases a neurotoxin that can cause dull pain, muscle cramping, and, in some cases, sweating and vomiting. Fortunately, fatalities from black widow bites are extremely rare, with fewer than 1% resulting in death.

First Aid for a Black Widow Bite

If bitten by a black widow, take these steps:

1. Apply an ice pack or alcohol to reduce swelling.
2. Clean the bite area with hydrogen peroxide or alcohol to minimize the risk of infection.
3. If possible, safely capture the spider for proper identification.
4. Seek medical attention at an emergency room.