More than 3,000 different spiders are found in North America, and more than 1,000 kinds live among us here in Utah. Only three or four of these eight-legged web spinners are a threat to us bi-peds. Most spiders are our pals, feeding upon insects and other small, soft-bodied invertebrates that are less scary, but more harmful than most spiders.

“Most spiders brought into my office for identification are in jars - either dead or alive,” says Jerry Goodspeed, Utah State University Extension horticulturist. “A few have arrived in envelopes or smashed in tissues. One particularly large spider was transported in a shoe box.”

If this were not challenge enough, he says he also is asked to identify spiders over the phone.

“Needless to say, it is challenging to calm and help a panicked voice explaining, ‘It's big, has different colors and looks really mean,’” Goodspeed says. “‘What kind of spider is it?’ Or, ‘I think it is poisonous because it is so ugly and disgusting looking. Is it?’ And my favorite, ‘I'm not getting close enough to tell you what it looks like. Just tell me what kind it is!’”

Although all spiders are poisonous, most are too small or have poison too weak to affect humans, he explains. The three spiders in our area that are harmful are black widows, aggressive house spiders and tarantulas.

The variety of tarantula that lives in Utah is actually non-aggressive and rarely bites, Goodspeed adds. And, when they bite, it usually causes temporary pain with no serious health problems. The mature female black widow spider is black, with two red spots on the underside of her abdomen. These spots are often connected forming the shape of an hour glass. They are generally not aggressive and only attack when disturbed or molested.

However, over the past five to seven years, the aggressive house spider or “hobo” spider has earned quite a reputation, Goodspeed says. They are most active in the summer and early fall months when males are often heard whistling “I’m in the mood for love.”

“They build funnel webs in the basement corners or on the ground floor of homes, rarely venturing up vertical surfaces,” he adds. “They are brown and are swift runners.”

Orb-weaving spiders are probably the largest and most colorful spiders in our area, Goodspeed says. In the garden they spin large webs which ensnare unsuspecting insects. They are harmless but imposing because of their size and color variations. Some may be larger than a quarter and adorned with yellow, orange, silver and white markings.

“Wolf spiders are probably the most common variety brought into our office,” he says. “Generally they are black or dark colored, able to move and run quite quickly, and found under rocks, logs or in small holes. They often live around water features, but inhabit most landscapes.”

The brown or gray spiders, which run around in the grass and cause children to scream, are called grass or funnel-weaving spiders, he explains. They build a funnel in the ground then wait to catch slow moving insects walking by. Their webs catch your eye as they sparkle in the early morning dew. Many beneficial spiders help keep insect populations in check. If you spot them in the garden, leave them alone to scavenger those undesirable bugs.

For answers to all your gardening questions go to http://extension.usu.edu/ccop/garden/
Utah State University Extension “Extending the University to You”