Polk County Conservation

Spiders

Worldwide, there are more than 35,000 species of spiders. Spiders, along with insects, crayfish, centipedes, millipedes, ticks and mites are in the phylum arthropod. Arthropoda means, “jointed legs”. Although spiders and insects are in the same phylum, spiders are not insects. Spiders have eight legs, do not have antenna, and only have two body parts. Insects have six legs, two antenna, and three body parts.

There are a wide variety of spiders in Iowa, and all are beneficial. It is estimated that one spider eats at least one insect a day, so collectively they have a significant effect in controlling the insect population. However, there are two species of spiders in Iowa that can be harmful. Continue reading to learn how to properly identify them. It is important to remember that even these spiders are highly beneficial animals.

The brown recluse, also known as the fiddle back spider, is a small brown spider with a characteristic violin shape on its back. The brown recluse lives in areas seldom disturbed by humans. When encountered, the brown recluse will usually not bite unless aggravated. Death from the bite of a brown recluse is extremely rare.

The other potentially dangerous Iowa spider is the black widow. Only the female black widow is capable of inflicting a dangerous bite. However, the female black widow is easy to identify. This small black spider has a red hourglass shaped spot on the underside of her abdomen. This spider, like the brown recluse will often flee when encountered. Death from a black widow bite is uncommon.

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Administration Office
11407 NW Jester Park Drive
Granger, IA 50109

P: (515) 323-5300
F: (515) 323-5354
pccb_info@polkcountyiowa.gov

Monday – Friday, 8:00 a.m. – 4:30 p.m.

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