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Integrated Pest Management · Agriculture and Natural Resources

University of California

Arachnids: Spiders, mites, and scorpions

Adult arachnids generally have eight legs, no antennae, and no wings, distinguishing them from insects. Some mites can be plant pests. Other arachnids may be pests of people and pets, or may be harmless or beneficial.

Link to mites


Mites are tiny and hard to see without a magnifying glass. They may damage fruit trees, vines, berries, vegetables, or ornamental plants.

Link to scorpions


Scorpions live in warm, dry climates and come out at night to feed on insects, spiders, centipedes, and other scorpions.

Link to spiders


Spiders are beneficial (although many people fear them) because of their role as predators of insects and other arthropods. Most cannot harm people.

link to ticks


Ticks can infest people or pets and may carry disease. Adult ticks seek their hosts from late fall to spring, but are most active during winter.

Link to windscorpions


These look like scorpions, but lack the long stinger tail. They are common in California's San Joaquin Valley and arid sections of the Southwest.