As predators spiders are beneficial......

Spiders are arachnids, a group of arthropods that also includes scorpions, harvestmen, mites, and ticks. Approximately 3,000 species occur in North America.

Spiders, like insects (another group of arthropods), have jointed legs and a hard external or outer skeleton. Spiders have four pair of legs, with a body divided into two regions (cephalothorax and abdomen), while insects have three pair of legs and the body divided into three regions: head, thorax, and abdomen. Spiders have no wings or antennae, but have enlarged, sharply pointed jaws called fangs (chelicerae).

All spiders are predators. They feed on a wide variety of insects and other soft-bodied invertebrate animals. Spiders attack and subdue their prey by biting with their fangs to inject a poison. As predators spiders are beneficial.

All spiders spin silk, but the silk is used in a wide variety of ways. Most spiders construct a silken case to protect their eggs, but not all spiders make a web. A few use silk threads much like a parachute to aid in dispersal on wind currents, e.g., balloon spiders.

All spiders are poisonous, but fear of all spiders is unwarranted because most are either too small or possess poison that is too weak to harm humans. Only a few have bites that are dangerous to humans. However, the bite of these few species can cause serious medical problems and possible death under certain circumstances.

The most dangerous spiders to humans in North America are the widow spiders (usually known as black widows) (Fig. 1), the brown spiders (also known as the fiddlebacked spiders), the tarantulas, an innocuous-looking sac spider, and a funnel-web spider.

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