Who needs them? We do--without them, insect populations would be totally out of control. They are the mightiest hunters of the arthropod clan; with or without their famous webs, their methods succeed against other insects who have a great advantage over the wingless spiders--flight.

Why are spiders so successful? Through a diversity of strategies--primarily active hunting and sit and wait --they can capture insects from all walks and flights of life.

Active hunters use their keen eyes to stalk their prey on the ground.

Jumping spiders (family Salticidae) use their large, forward-facing eyes to spot prey from a distance, then leap upon their victim.

Ambush predators, crab spiders (family Thomisidae) conceal themselves on flowers and wait for unsuspecting morsels to walk by.

The largest and bulkiest tarantulas are the giant bird-eating spiders (Theraphosa blondi) from Northeast South America. Many tarantulas are called bird-eaters, even though birds are not part of their regular diet.

Mexican red-knee tarantulas (Brachypelma smithii), like many other tarantulas, take 10 years to reach maturity. All male tarantulas die soon after maturing, but females can live to hunt for 10-20 years. This species has been placed on the Convention for Threatened and Endangered Species (CITES) list.

Sit and wait hunters include the web-spinners, who compensate for poor eyesight and sedentary ways by spinning silken tangles and sheets to enlarge their dinner plates.

The dense hackle bands woven by Kukulcania hibernalis trap prey like Velcro. They are made of a special, dry silk called catching--or cribellate--silk.

The spring trap of the triangle spider (Hyptiotes) is made of dry, or cribellate, silk. The spider forms a living spring between the tension thread and the attachment threads. When prey lands on the web, the spider releases the tension--collapsing the web around the prey.

The hammock web of the bowl and doily spider (Frontinella pyramitela) traps prey who fall into its stickey, tangled lines. The spider bites the victim and pulls it through the web.

The scaffold web of Steatoda has gluey droplets at the base of the attachment lines. An insect unfortunate enough to wander into one of these lines gets stuck and breaks it. The spider then hauls the victim up into the web.

The typical orb web of the garden spider has sticky spirals and dry spokes with zigzag bands crossing the web. Mangora gibberosa weaves a tight web to resist the high impact of fast-moving prey like the blue bottle fly.

The loosely-woven orb web of the ray spider (Mangora gibberosa) is designed to resist low-impact or small prey like midges and mosquitoes. The spider pulls the center down to form an umbrella shape. When an insect lands, the spider lets go. She and the web spring back and ensnare the prey.

Why don't spiders stick to their own webs? Sometimes they do. But they are experts at getting out of sticky spots. It also helps to have oily feet and dry spokes. Spiders can hop-scotch around possible traps.