Spiders have certain characteristics that set them apart from insects: they lack wings and antennae, have eight legs instead of six and instead of jaws, they have fangs. In Iowa, there's a variety of spiders to be found, although fortunately the most poisonous like the black widow are not. Still, there are some spiders that should simply be avoided at all costs, while others can be admired from a distance. Here are some ways to recognize spiders found in Iowa.
Look for fisher spiders at the edges of streams and lakes, or gliding across the surface of the water. Though sometimes fisher spiders will dive and attack water bugs and even tadpoles, they mostly eat insects found on plants that grow near the water's edge. Commonly found in Iowa, fisher spiders are mostly brown and very hairy, with stripped legs and gray striping along their bodies. They do not spin webs, but hunt by injecting poison that dissolves the inside of the prey's body, so they can suck the liquefied remains. They rarely attack humans, and are not poisonous, but will bite if provoked.
Find wolf spiders in tall grass and shrubs. Another spider commonly found in the outdoors of Iowa (though like fisher spiders, they too will sometimes come indoors. Their are 1 or 2 inches long, and are solid brown or sometimes lightly stripped. They have 4 small eyes in one row, 2 large eyes in the next row, and 2 medium-sized eyes in the row above. You will not find wolf spiders spinning webs; instead, like fisher spiders, they hunt for their prey and jump to overtake them. Mother wolf spiders carry their newborn on their backs until they grow bigger. Though they rarely bite, when they do, swollen lymph glands may develop as a reaction, and swelling around the bite can last up to 10 days.
Beware of brown recluse spiders in Southern Iowa. You can recognize them easily by the violin pattern near the adult spider's head, and their legs have very fine hairs without any color markings like bands or streaks. Also, unlike a lot spiders, they have 6 eyes that are arranged in pairs. They mostly make their webs in hidden places and rarely out in open spaces. Though most people when bitten do have too strong of a reaction, depending on how deep the bite and how much venom was injected, sometimes a painful reaction can occur a few hours after the bite. If it begins oozing, seek medical attention.
Know that daddy long legs might not be "true" spiders, but are arachnids. You'll see them mostly in autumn, crawling quickly on their long, thin legs, especially in basements. They do not spin webs and are harmless, as they have no venomous glands. While they can pinch your skin, rarely can they penetrate it. Unlike other arachnids, they mostly scavenge for their food, feeding on insects already dead and will even suck juices out of vegetables.