Poisonous Spiders Found in Indiana

Spiders may have a bad reputation, but only a few spider species in the United States are capable of harming humans. Only three of those species are in Indiana: two black widow species and the brown recluse. According to Purdue Extension, about 400 spider species live in the state, which means dangerous spiders make up only 3/4 of 1 percent of those species. Still, Indianans may encounter the dangerous spiders indoors or outdoors, including while gardening or doing other work in their yards.

The two species of black widow spiders that inhabit Indiana are the southern black widow (Latrodectus mactans) and the northern black widow (Latrodectus variolus). The southern black widow inhabits most of the U.S. South and Southeast while the northern black widow inhabits most of the eastern United States.

Females of both species have a shiny, round body with red markings on the underside of the abdomen. The southern widow's red markings usually form a complete hourglass shape; the northern widow's red markings are usually two distinct patterns on the underside of the abdomen and a row of red dots on the abdomen's upper side.

Females can grow 1 1/2 inches long with their legs fully extended. Male and juvenile black widows have irregular markings, including stripes and blotches. Adult males are barely one-half the size of adult females.

Black widow spider females are relentless guardians of their egg sacs; despite that trait, however, they are typically shy and try to flee human interaction in other cases. Female black widows most often build their webs in low-to-the-ground areas, such as around water spigots, under steps and, in some cases, outdoor furniture. They also seek sheltered areas, such as inside outbuildings.

Most black widow spider bites in humans occur when people extend their hands into or close to guarded webs.

The female and male black widow's venom, which is delivered through a bite, is a neurotoxin that affects nerves. The bite's severe reaction has become manageable with the invention of antivenin specific to the dangerous venom. A variety of symptoms may happen following a black widow bite:

Abdominal cramping

Dizziness

Sweating

Nausea

Vomiting

The much-feared brown recluse spider (Loxosceles reclusa) is seldom seen, much due to the species' reclusive nature and habit of staying out of sight. A mature brown recluse spider's body -- not including legs -- is about 3/8 inch long, and its body's width is about one-half that measurement. Most adult specimens are very light tan to a darker, reddish brown. Known for the violin- or fiddle-shaped marking behind their eyes, these spiders are also called "violin spiders" and "fiddlebacks". The fiddle-shaped marking is typically darker than the rest of the body but is not always visible.

The natural range of the brown recluse is only a small portion of the United States, from southern Iowa south through most of Texas, east through the northern one-half of Georgia and up to central Indiana and a small portion of southwestern Ohio. Some specimens, however, have been recorded outside of that region, most likely transported in moving boxes or in a similar manner.

A bite from a brown recluse often happens when a human sticks her hand into its hideaway, such as in a brush or debris pile, or inside a garage or outbuilding, or when the spider is hiding in clothing and gets pressed against skin.

The venom of brown recluse spiders is much different from that of black widow spiders. Following a bite from a brown recluse, the victim may experience several severe effects:

Extreme pain at the bite wound

Small, white blister at the bite wound

Inflamed tissue around the wound, with the inflammation spreading

Tissue around the wound becoming hard to the touch

Affected tissue dying and peeling away, leaving a sunken, dead-tissue sore up to the size of a one-half dollar coin

Seek immediate medical attention if you notice any of the symptoms characteristic to the bites of either of these spiders, or if you see one of these spiders bite you.

If you are bitten, use mild soap and water to clean the wound, and apply a cold compress to reduce pain and swelling. An over-the-counter medication such as acetaminophen or ibuprofen also can help with pain. If you can do so safely, collect the spider in a jar or other container for its proper identification by professionals.