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Rural Living for August 20, 2009


by Carol Dunn

Spiders feed on insects, so they are beneficial to have around your homestead.  Although their webs are sometimes pesky, they do catch flies and other insects.  Nonetheless, many people are squeamish about having spiders around the house.

    Thirteen spiders are found in Colorado: Funnel weavers, Jumping spiders, Wood louse hunters, Ground spiders, Cobweb or House spiders, Widows, Brown recluse, Banded garden spiders, Cellar spiders, Orb weavers, Sac spiders, Wolf spiders and Tarantulas.  For photos, go to the Extension website: .

    Most westerners are aware that wild tarantulas will bite when handled.  These bites are similar to a bee sting but can occasionally produce an allergic reaction.  Wood louse hunters, sac spiders, and wolf spiders will also bite, and the bites can be painful, but they are not harmful.  The first aid treatment is rest, ice, compressions and elevation.

    The Western black widow is the most common species with venom that is harmful to humans.  It is easy to recognize because it looks like a tiny, shiny black marble with a small head and a red hourglass shape on its abdomen. The female is often found hanging upside down in her disorganized web, which makes it easy to see the red marking.  Widow venom is a nerve poison, and a bite will cause sharp pains in the arms and legs, cramping of stomach and facial muscles, and profuse sweating. Black widow bites are rarely fatal unless you are allergic to the venom.  Antivenin will eliminate the symptoms, but physicians are hesitant to administer it unless they are sure it is a widow bite.  So if you are bitten, take the culprit with you, even if you have squished it, so the doctor can examine it.  According to Sherry Gomez, Director of Emergency Services at Spanish Peaks Regional Health Center, the Walsenburg facility does not have Black widow antivenin on hand because it is in limited supply and only provided to the larger hospitals.

    Several sources confirm that the Brown recluse native range includes the area from southeastern Nebraska south to Texas and east to Georgia.  But they are occasionally found on the outskirts of that range in Colorado because they inadvertently get packed up and moved in boxes on moving day, and Colorado is a popular destination.  The Brown recluse is shy and will bite humans only when it is injured or provoked.  This usually happens accidentally, when a person reaches into hay bales, wood piles, drainage passages, among feed sacks, under houses, and other hiding places.  Brown recluse venom has an enzyme that dissolves its prey for easier eating, so it causes the tissues around the bite to essentially rot.  Brown recluse bites are difficult to treat and cure, and rarely the venom can cause kidney failure.  Wearing gloves is one way to avoid a nasty Brown recluse bite.

    Spiders are a valuable bug control resource.  However, if you want to get rid of spiders in your home, you will need to remove their favorite habitats near your house, like piles of rocks and firewood and stacks of bricks and lumber, caulk, foundations, and cracks and around windows and doors.  Make sure your weather stripping is in good shape.  Vacuum or broom away spider webs.  You can also use an insecticide specifically labeled for spiders.