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How to Identify Spiders in Northern California

There are over 50,000 species of spiders in the world. Contrary to popular belief, it is not easy to identify most spiders based on their markings. Trying to identify a spider based on its color is similar to identifying the model of a car based solely on its color. Most spiders found in California are not dangerous, except to people allergic to spider bites. Dangerous spiders like the Brown Recluse are generally not found in California, despite what you may have heard.

Things You'll Need

Magnifying glass

Instructions

- 1
  
  Count the eyes of a spider. Most spiders in the United States have 8 eyes in two rows of 4 eyes each. A Brown Recluse spider has 6 eyes set in pairs.
- 2
  Look for coloration and pattern. Do not depend on this as your only means of identification, though. Some young spiders may have no color or pattern that is visible. Brown Recluses are known for a violin shape, which does not refer to a color pattern but to the shape of their abdomen or cephalothorax. A Spitting spider looks similar to a recluse and has 6 eyes, but has black stripes and is non-poisonous.
- 3
  Look past the violin pattern. Many non-poisonous spiders also have a tell-tale violin pattern. Unless the spider has the combination of a violin pattern and 6 eyes, it is probably non-poisonous.
- 4
  Count the major body parts. Daddy Long Leg spiders have a single body, as opposed to spiders that have two sections. Daddy Long Legs have no venom glands and do not spin webs.

Insects & Science