Technically speaking, spiders are neither insects nor bugs. Rather, they belong to a group of insect-like creatures called Arachnids, which also includes scorpions, daddy-long-legs, mites and ticks. Unlike insects, spiders lack wings, an insect's segmented, three-part body; and have four pairs of legs instead of  three.

Anatomically, spiders are wonderfully well equipped to catch, kill and eat all kinds of insects- from tiny, snack-sized critters such as earwigs, to larger, heartier fare such as cockroaches. Though some spider species hunt or ambush their prey and a few are capable of killing birds, snakes and small mammals, the overwhelming majority capture insects in the manner with which we are all familiar. They spin webs of silk to trap their prey, then inject the defenseless victim with venom to subdue and ultimately kill it. The spider's hooked, open-tipped fang (or fangs, depending on the species) not only does the job of perforating an insect's tough outer shell, but also pumps deadly poison into the wound by means of a short duct connected to a venom sac.

Despite the spider's skill and efficiency as a predator of insects, just a handful of the world's 30,000 spider species are known to bite humans or have the capacity to harm us greatly. Those select few, however, can do some real damage, inflicting bites that range in severity from painful (but not injurious) to lethal.