Guide to Identifying White Spiders Commonly Found in Iowa

White Spiders Commonly Found in Iowa

Iowa is home to a variety of spider species, some of which have white or light-colored markings. While most Iowa spiders are harmless, a few do possess a potentially medically significant bite. This article will focus on identifying the most common white spiders found in Iowa and providing key facts about their appearance, habits, bite risk and web types.

Orb Weavers

Orb weaver spiders belong to the family Araneidae and are one of the most common groups of spiders in Iowa. There are over 170 species of orb weavers in North America, many of which have white or silver markings on their abdomen or legs. Some examples include:

• Barn Spider - Silver and black markings with a large orb web.
• Garden Spider - Prominent white stripes on a black abdomen and legs.
• Marbled Orb Weaver - White, black and orange markings with a distinctive bulbous abdomen.
• Cat-Faced Orb Weaver - Abdomen has white bands resembling a cat's face.

Orb weavers construct large, intricate webs in outdoor areas like gardens, between trees and on porches. They help control insect populations and are not considered dangerous to humans.

Fishing Spiders

Iowa is home to multiple species of fishing spiders that inhabit moist areas near lakes, streams and marshes. They do not build webs but instead actively hunt for prey along the water's edge. Some fishing spiders have white stripes and markings such as:

• Six-Spotted Fishing Spider - White stripes on dark brown body and legs.
• Raft Spider - Grayish-brown body with white markings on the abdomen.
• Nursery Web Spider - Light brown with faint white striping on legs.

Fishing spiders may bite if threatened but effects are usually mild, similar to a bee sting. They use their excellent eyesight to detect prey while waiting motionless at the water's edge.

Wolf Spiders

Iowa has around 20 species of wolf spiders, which actively hunt instead of building webs. Some have camouflaging white or grey colors such as:

• Carolina Wolf Spider - medium to large in size, gray and brown stripes.
• Rabid Wolf Spider - vibrant white stripes on jet black body.
• Tigrosa Wolf Spider - small, patterned black and white markings.

Female wolf spiders carry egg sacs on their spinnerets until spiderlings hatch. Wolf spiders deliver a painful but mostly harmless bite if carelessly handled.

Crab Spiders

Over 1,000 species of crab spiders exist worldwide, most having a laterigrade (sideways) walking motion. Some crab spiders found in Iowa include:

• Goldenrod Crab Spider - White, yellow and red coloring that blends with flowers.
• Flower Crab Spider - White/pink, waits on flowers to ambush pollinators.
• Spined Micrathena - Bright white abdomen with funky spiky appearance.

These ambush hunters do not build webs. They can inflict a bite but are not aggressive and very rarely bite humans unless provoked. The bite causes mild pain and swelling.

Web Types of Common White Spiders

Different types of spiders spin different kinds of webs suited to their hunting tactics. Here are some common web types you'll notice:

Orb Webs

Orb weaver spiders construct intricate, circular webs with spokes radiating out from a center hub. An orb web allows the spider to efficiently capture flying insects while remaining stationary at the center.

Cobwebs

Cobweb spiders build messy-looking, tangled webs in undisturbed corners of sheds, attics and crawlspaces. unlike orb-weavers, cobweb spiders hide away in a retreat waiting for prey to blunder into strands.

Funnel Webs

Funnel weaver spiders make horizontal webs shaped like a funnel or tubular tunnel, usually building them in a crevice or hole. The spider waits unseen at the small funnel opening to ambush prey.

Sheet Webs

Sheet web spiders construct large, flat horizontal webs attached on one side to a structure. Some build their sheet webs in tall grass. The spider waits underneath the sheet web and senses vibrations of prey above.

No Web

Some spiders like wolf spiders, fishing spiders and crab spiders do not spin webs at all. They actively hunt instead, relying on excellent eyesight and speed.

Identifying and Avoiding Dangerous Spiders

While most spiders in Iowa are not considered dangerously venomous, there are two spiders of medical significance:

Brown Recluse Spider

The venomous brown recluse spider is found in Iowa, usually in woodpiles, sheds and undisturbed storage areas. It has a dark brown body with a distinctive violin shape on the cephalothorax (combined head/thorax area).

The brown recluse delivers a hemotoxic venom that can cause necrosis at the bite site. Seek medical attention if bitten by this spider.

Black Widow Spider

The black widow is a timid but venomous spider found in Iowa and other central states. Females have a shiny black body with a prominent red hourglass marking on the underside. They build messy webs in undisturbed spots.

The neurotoxic venom of a black widow bite can cause muscle rigidity, abdominal pain, and breathing difficulties in severe cases. However, antitvenom is available.

Here are some tips to avoid spider bites when cleaning attics, basements and sheds:

• Wear gloves, long sleeves and pants.
• Use caution moving woodpiles or debris.
• Knock down webs with a broom before entering.
• Vacuum up spiders and webs.
• Seal entrances spiders could use.

Most spiders play an important role controlling insect populations and are harmless if left alone. Learning to identify local species can prevent needless fear or destruction of beneficial spiders around your home.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.