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.
Mites
Mites are tiny and hard to see without a magnifying glass. They may damage fruit trees, vines, berries, vegetables, or ornamental plants.
Scorpions
Scorpions live in warm, dry climates and come out at night to feed on insects, spiders, centipedes, and other scorpions.
Spiders
Spiders are beneficial (although many people fear them) because of their role as predators of insects and other arthropods. Most cannot harm people.
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.
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.
