Spiders are feared by many people, and on occasion, that phobia can be justified. If you live in a region where you can encounter the wrong spider—such as a black widow or a brown recluse—a painful bite or visit to the hospital is a distinct possibility.

A cobweb dangling in your face or a spider crawling up through the bathtub drain is nobody's idea of fun, so it's understandable if you want to get rid of spiders when they appear inside the home.

Although often considered insects, spiders are actually arachnids, with eight legs rather than the six found in insect species, and two main body parts vs. the three parts common to all insects. And virtually all spiders are carnivores, with fangs to kill prey.

Pyrethrin, a natural pest repellent spray made from extracts from chrysanthemum flowers, will kill spiders (and other pests) if they receive a direct hit.

Risks Spiders are typically a nuisance rather than harmful. They reproduce quickly and create cobwebs in hard to reach areas. Most species use their venom on invertebrates rather than humans. Most spiders are harmless and the bites cause localised pain, redness and swelling. Humans can have allergic reactions which includes feelings of nausea, dizziness and in extreme cases, necrosis.