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Spiders are a diverse group of arachnids.  Most use silk to catch the live prey they eat.  The Orbweavers form the familiar orb-webs most people associate with spiders.  Other spiders use the silk they create to build different kinds of webs.  Black Widow spiders create very random-looking webs that make no sense when compared to those of orb-weavers.  Funnel-web spiders create webs with a sheet of silk that leads gradually to a smaller tunnel where the spider waits.  When a prey item falls or walks upon the sheet, the spider rushes out and catches the victim. 

Many other kinds of webs are built by spiders, and different kinds of silk are used by the females to construct egg sacs.  Bola spiders swing a sticky kind of silk on the tip of a silk string at their prey, catching them in mid-air!  Of course, silk is also used as a safety-line if a spider falls or needs to drop to get away from a predator.

Trapdoor spiders line the vertical shaft of their tunnel with silk to provide structure, and attach the "trapdoor-lid" over the hold in the ground with silk, so that it hinges at the edge.

Daddy-longlegs are NOT spiders.  They are Harvestman (Opiliones), a different kind of arachnid, as are scorpions.  These are the long-legged arachnids with disc-like bodies that you see outside, in your backyard.  The long-legged spiders that you see in webs in your garage or basement are called Cellar Spiders and these are true spiders, with more elongated bodies.

Spiders have a very bad reputation in the United States, with fears being exaggerated greatly by the media and even by parents who pass on a culture of fear to their children.  Only four spiders in the US are of serious medical importance.  In the Southern and South-Eastern parts of the country, the Fiddle-back spider, also known as the Brown Recluse is of concern.  In the Pacific Northwest, the Hobo Spider gets a lot of press.  It can cause damage to victims to the same extent as the Brown Recluse with cases of people losing limbs to necrosis being rare, and death being extremely rare.  Black widows can cause death, but it's mostly the pain that gets our attention.  They occur in arid parts of the country.  Few people die from the bites of any of these spiders. 

The yellow-sac spider is the most common "biter" in North America.  We see them around our porchlights at night and in the corners of our rooms.  They are more common than these other spiders and so are the cause of bites more often.  Symptoms are sometimes equal in severity to bites from the other three spiders.  Usually, it is the sick, elderly or very young that have serious complications.  Most people have never been bitten by a spider, but falsely attribute a bite that doesn't go away for a few weeks as a spider bite.  Often, a spider bite will have a noticeably hardened "lump" or mass in the center of the bite area.  When spider bites do occur, it is important to go to the doctor, especially if a red-line begins to appear from the bite and going in the direction of the heart.  This is not a reaction to the venom, but a secondary lymph-system infection caused by bacteria that entered the wound.  Antibiotics will be required to kill the infection.

I'll try to put some pictures of these spiders up soon.

Spiders are beneficial organisms that help maintain a balance in the ecosystem that includes insects and plants, animals and humans.  In a world of sidewalks and manicured lawns, they are one of the few wild animals that we still see in our backyards.