Many species of spiders are common residents of Oklahoma gardens. Nearly all of those species are entirely harmless, but the bites of two spider species found in Oklahoma can cause serious, sometimes even fatal, reactions.

Redback Spider
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Black widow on a log

Brown Recluse

Stone wall
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Stacked brick wall in garden

The brown recluse or fiddleback (Loxosceles reclusa) is a shy spider that, in the garden, tends to hide in areas with low activity, such as under rocks and logs. It also may be in garden sheds and barns. It emerges from hiding to hunt most often at night.

A brown recluse is light or dark brown and about 1/2 inch in body length. Its most apparent distinguishing feature is a dark, fiddle-shaped marking extending from the back of its head toward the read of its body.

The bite of a brown recluse may or may not be painful at first but will likely become painful. A small blister will form over the site of the bite within 24 hours, and the area around the bite will become red, swollen and painful. In severe cases, an open, slow-healing sore may develop around the site.

Southern Black Widow

black widow
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Black widow on a wooden fence

The southern black widow spider (Latrodectus mactans) is also a reclusive species and rarely leaves its tangled web. In the garden, the spider is often found under rocks and woodpiles or beneath low-hanging foliage.

The female southern black widow has a body length of about 1/2 inch and is glossy black. On the underside of its abdomen, it typically has a pair of bright red, triangular markings that often meet in the middle, forming an hourglass shape. The male of the species is about one-half the size of the female and usually has light streaks on the sides of its body.

Although the bite of a male southern black widow is not dangerous, the bite of the female injects a neurotoxin that can cause a severe reaction. Symptoms of the reaction may include severe pain and cramping, vomiting and difficulty breathing. Healthy adults usually recover from the bite within a few days, but in vulnerable individuals, such as children and the elderly, the reaction can be fatal.

Non-Dangerous Spiders

Black spider on the ground
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Tarantula on the ground

Some species of spiders in Oklahoma are often thought to be dangerous but in fact pose no threat to humans.

For example, tarantulas, large spiders in the genus Aphonopelma, may be fearsome in appearance, but their venom typically causes no serious problems in humans. These spiders are black or dark brown, hairy and over 3 inches long when full size. They roam in search of prey at night and hide under rocks and in burrows during the day.

Wolf spiders of the genus Hogna are also large, with body lengths sometimes exceeding 1 inch. They are typically brown and hairy, and some species have darker stripes on their backs. Their hunting and hiding behaviors are similar to those of tarantulas. Wolf spiders are sometimes mistaken for brown recluse spiders, but they lack that species' distinctive fiddle-shaped marking. Although wolf spiders move swiftly, they are not aggressive and rarely bite.

First Aid

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Two aspirin tablets in someone's palm

If you think you may have been bitten by a black widow spider, then seek help from a medical professional immediately. Typical treatment of the bite includes the application of ice to reduce swelling and an over-the-counter pain reliever to treat pain. In the case of an exceptionally severe reaction, antivenin may be administered.

Appropriate first aid for a brown recluse bite also includes the application of ice and the use of a pain reliever. Seek medical attention if an open sore or blackening of tissue occurs at the site of the bite, or if you develop any symptoms that involve your entire body.