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Truth about spiders: Most are harmless

Often the Extension office receives calls regarding spiders and the concern from homeowners about whether they are poisonous or not. There are many species of spiders native to our area, but only a few are poisonous to humans. Spiders play an important role in the environment eating pestiferous insects.

Only two species of spiders endemic to our area are poisonous, the black widow and the brown recluse spider.

The black widow is the most common. They spiders spin irregular webs in crevices and other dark, protected spots, such as woodpiles and under rocks. They are sometimes found indoors in attics, basements and under cabinets. It is roughly 1/2 inch long, and is a shiny black color with a red hourglass mark on its abdomen. The male is small and of no threat to people. The female spider can bite, and it is poisonous to humans. The bite is followed by pain and swelling, nausea and difficulty in breathing but is rarely fatal.

Bite victims need to receive medical treatment as soon as possible. Children and the elderly are more susceptible to the bites than healthy adults. The spider is not aggressive and only bites when provoked. Be careful about leaving boots and shoes outside or in garages for long periods of times. These spiders have been known to move in and make themselves at home. The unknowing person puts the shoe on and is bitten by the spider.

The other poisonous spider is the brown recluse spider. These spiders are sometimes referred to as "fiddleback" spiders or "violin" spiders since the top surface has violin-shaped markings. They are about 1/4 to 3/4 inch long. They are reclusive, shy spiders that prefer quiet, undisturbed places. They range from the central Midwestern states southward to the Gulf of Mexico. In Georgia, they are found mainly in western and northwestern parts of the state, and are not common in these areas. Just because a spider is brown and has marks on it does not make it a brown recluse spider. The bite of the brown recluse is poisonous to people. Victims often become ill and find that the wound does not heal quickly. The bitten area becomes painful, and eventually turns black as the skin cells die off. It leaves a depression and unsightly scar tissue. Sometimes it has to be treated by a surgeon. However, actual brown recluse spider bites are not common in Georgia. Often, the bites can be mistaken for other skin infection, including methicillin-resistant Staphylococcus aureus (MRSA). So, if someone has a skin tissue infection, best to check out other possible causes before jumping to conclusion the bite is a result of a brown recluse or other spider.

In conclusion, most spiders do not harm people, and the two poisonous species seldom cause injury. To control spiders, keep closets, basements, attics and other areas of the home cleaned. Outside, remove wood piles, old boards and other debris from around the home and in areas where children play. Keep vegetation cut back away from structures, and mow the grass frequently. Homeowners discourage spiders from taking up residence by destroying webs and spiders by brushing or vacuuming them. Caulk or seal openings on the sides of the house to keep them out. If the problem persists, consider consulting with a pest control service or contact the Extension office.

Timothy Daly is an agricultural and natural resource agent with the Gwinnett County Extension Service. He can be reached at 678-377-4010 or timothy.daly@gwinnettcounty.com.