Natural Enemies Gallery

Spiders

Hosts or Prey

A wide variety of insects, spiders, and other arthropods

Identification

Spiders have two main body parts, the abdomen and cephalothorax (head and thorax combined). They have four pairs of legs and leglike appendages in front called palps.

Most spiders have eight eyes, and their arrangement and relative size help to distinguish the spider family. Some groups have only two or six eyes. Some cave-dwelling spiders lack eyes. Whether or not spiders spin a web, and if so what type, also helps to distinguish the family.

Life Cycle

Spiders hatch from an egg and develop through five or more spiderling (immature) stages before maturing into adults.

Habitat

Some species capture prey in silken webs. Others stalk insects across the ground or vegetation or lay in wait and pounce on prey.

Spiders seek to avoid people. Most spiders are harmless to humans and are beneficial because they consume insects. To minimize encounters with potential­ly hazardous recluse and widow spiders, reduce clutter near entranceways and near the ground.

If spiders are coming indoors, see Integrated Pest Management Checklist for Early Care and Education Programs (PDF) from UC San Francisco and Pest Notes: Spiders from UC IPM. These list steps to take in and around buildings to eliminate or greatly reduce arthropods coming inside. For example seal cracks and crevices through which insects and spiders enter buildings. To manage spider problems use integrated pest management (IPM).

Species

At least 54 families and over 1,000 spider species occur in California.

More Information

Scientific classification:

  • Phylum: Arthropoda
  • Class: Arachnida
  • Order: Araneae
Adult flower spider, Misumena vatia (Thomisidae).
Adult flower spider, Misumena vatia (Thomisidae). Credit: Jack Kelly Clark, UC IPM Program
Adult funnel weaver spider, Hololena nedra (Agelenidae).
Adult funnel weaver spider, Hololena nedra (Agelenidae). Credit: Jack Kelly Clark, UC IPM Program
Adult jumping spider, Phidippus audax (Salticidae), eating a fly.
Adult jumping spider, Phidippus audax (Salticidae), eating a fly. Credit: Jack Kelly Clark, UC IPM Program
Webbing of a cobweb weaver spider (Theridiidae) capturing adult greenhouse whiteflies, Trialeurodes vaporariorum.
Webbing of a cobweb weaver spider (Theridiidae) capturing adult greenhouse whiteflies, Trialeurodes vaporariorum. Credit: Jack Kelly Clark, UC IPM Program
Cobweb weaver spider (Theridiidae) adult, egg sac, and hatching spiderlings.
Cobweb weaver spider (Theridiidae) adult, egg sac, and hatching spiderlings. Credit: David Rosen