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Most Dangerous Animals in Iowa

When you picture Iowa, deadly creatures are probably not the first thing to come to mind. Despite its miles of rolling farmlands and peaceful countryside, the Hawkeye State has its share of wild animals that can cause injury or illness to humans.
We’ll cover the deadliest animals in the state of Iowa, what makes them dangerous, and how to stay safe around them.


Iowa has nearly 30 different snake species that can be found throughout the state, but only four of them are venomous. Many of them are considered protected species, meaning that it is illegal to catch or kill them in most counties.

Timber rattlesnakes

Timber rattlesnakes are large–often measuring between 36 and 60 inches long–and dangerously venomous. They are typically yellow, gray, or brown with thin black bands that run across their backs. These snakes live in eastern and southern Iowa, usually found in rocky bluffs.

Fortunately, timber rattlesnakes will not attack humans unless very threatened. In most cases, they will attempt to avoid humans by hiding rather than biting.

Eastern massasauga

Eastern massasauga snakes are quite rare in Iowa—they used to be more common, but their population has fallen significantly in recent decades. They are usually brown or gray with black or dark brown spots. They typically have a small, dark-colored rattle that doesn’t stand out from the rest of the snake’s body.

These snakes are most often found in grasslands and meadows, usually not too far from water. During winter, they move into swampier areas near lakes and rivers.

Like timber rattlesnakes, eastern massasaugas can be found in eastern and southern Iowa. Because they are endangered, the Department of Natural Resources encourages citizens to report sightings of the snake, even if it is dead.

Prairie rattlesnake

Another endangered snake, the prairie rattlesnake is typically tan, brown, or green with dark brown blotches. This snake’s range in Iowa is limited to the area in and around the Broken Kettle Grasslands Preserve on the western side of the state.

Prairie rattlesnakes, true to their name, make their habitat in prairies and grasslands. They are not quick to bite—with enough warning, they will hide rather than strike. They will often warn humans and large animals by shaking their rattle before attacking.

Copperhead snake

According to the Iowa Department of Natural Resources, the copperhead snake is the rarest species of snake in the state. Their natural habitat is confined to the southeast part of Iowa, usually in bottomland forests and near the Mississippi River.

Staying safe around venomous snakes

Wear sturdy boots and long pants when hiking in wooded areas or in tall grass. Stay on designated paths and be cautious when stepping over logs or rocks. If you encounter a snake, venomous or not, back away slowly and give it space. Do not attempt to catch, hurt, or kill the snake.

If you are bitten by a snake, seek medical attention immediately. Many snake bites are not medically significant to humans, but err on the side of caution by having it checked. Even a bite from a non-venomous snake can become infected.


Like many animals, the two most venomous spiders in Iowa only bite when threatened. Unfortunately, because they are so small, many people don’t realize the spider is there before it bites. Most commonly, spiders will bite when a human reaches into its home—dark, quiet places like crawl spaces or rarely used shoes.

Black widow spider

Black widow spiders are perhaps the most easily recognized spider in America, with the exception of the tarantula. Their black body with the signature red hourglass on their bellies makes them immediately identifiable.

Brown recluse spiders

While brown recluse spiders are not as venomous as black widow spiders, they are sometimes considered the more dangerous of the two. This is due to their appearance—they are not as recognizable as the black widow, meaning that some people do not realize their danger upon seeing them.

The brown recluse is usually yellowish or grayish brown. Their most distinctive feature is a dark brown violin-shaped mark near the back of their heads. For this reason, they are sometimes called fiddlebacks.

Brown recluse spiders have a range centered in the American South—in Iowa, they can typically only survive indoors and are not often found north of the bottom third of the state.

Staying safe around venomous spiders

Wear gloves and long sleeves when working in areas where spiders may hide, such as basements, garages, and sheds. Use caution when reaching into dark or hidden spaces.

Fortunately, black widow and brown recluse bites rarely cause fatalities in healthy adults. In small children or elderly people, however, the venom can be more dangerous. Seek medical attention if bitten.
Wasps on a piece of wood

Insects and Other Bugs

Most insects will not injure or kill you just by biting you. Many, however, carry diseases that make humans seriously ill.


Mosquitoes are one of the deadliest insects on earth. They carry malaria, West Nile virus, and Zika virus, diseases that, depending on severity, can cause serious illness, death, pregnancy complications, and lasting health issues.


Sometimes called yellow jackets or hornets, wasps are, in fact, venomous animals. They are important pollinators, but can be aggressive toward humans. Their sting is often painful, but rarely deadly.

The biggest concern with wasp stings is allergic reactions. People who have allergies to bees or wasps should keep a bee sting kit with them and know how to use it. If you are stung by a wasp and start to experience difficulty breathing or rapid heart rate, seek medical attention immediately.


Ticks are tiny arachnids that latch onto the skin of humans or animals and suck their blood. Their bite is not generally considered to be venomous, but they carry dozens of diseases that can be passed on to humans and pets.

One of the most common tick-borne diseases in the world is Lyme disease. Other diseases from tick bites include babesiosis, Rocky Mountain Spotted Fever, and Southern Tick-Associated Rash Illness.

Preventing bug bites in Iowa

Wear insect repellent when recreating outside, especially in the summer and fall. When walking through tall grass or forests, consider wearing pants and long sleeves to protect your limbs. After spending time outdoors, check your skin for ticks (and do the same for your pet dogs).

If you see a wasp, give it plenty of space. If you find a wasp nest in a dangerous area, call pest control to have it removed.


Coyotes are not usually dangerous to humans, but may attack pets, livestock, or small children. This is especially true as their habitats are encroached upon. A frightened, sick, or injured coyote may bite if approached.

Keep small pets indoors or supervised when outdoors. When out for hikes or walks, keep dogs leashed—hungry coyotes may try to lure them back to their den, where the rest of the pack waits. If you encounter a coyote, make noise, maintain eye contact, and back away slowly.

White-Tailed Deer

White-tailed deer are abundant in Iowa’s woodlands and fields. Deer will not attack or bite humans, so it may seem surprising to find them on a list of dangerous animals. It is possible, however, that they are responsible for the deaths of more humans than any other mammal on this list.

In 2020, nearly 200 people in the U.S. were killed in car accidents involving animals such as deer. A recent study found that Iowa and nearby Minnesota rank in the top ten for accidents involving wildlife.

Driving safely in deer country

Deer are most likely to be seen in rural areas. They are most active around dawn and dusk, when visibility is low, so be very vigilant when driving at these times of day. Keep an eye out for deer crossing signs.

If you are involved in a car accident with a deer, move your car to safety if possible and check for injuries. If the crash caused serious injuries, call 911 immediately.


While domestic dogs are beloved companions, they can pose risks if not properly trained or supervised. Unattended or unrestrained dogs may exhibit aggressive behavior, leading to bites or attacks.

Safety tips for interacting with dogs

Avoid approaching unknown dogs, especially if they are growling or behaving aggressively. If approached by an aggressive dog, do not run. Instead, avoid eye contact and back away slowly. Try to get large objects, like parked cars or garbage cans, between yourself and the dog.

Ensure that your own dog is well-trained and properly restrained when in public spaces. Keep your dog on leash unless in a designated off-leash area. Even when using off-leash parks and trails, make sure you can see and call to your dog at all times.

If you are attacked by an aggressive dog, seek medical attention right away and report the bite to your local animal control department. Consider contacting a personal injury attorney to discuss the possibility of an injury claim.

The Iowa Advocates offer free consultations—it will cost you nothing to speak with one of our experienced attorneys. We can explain the claims process and help you understand your options. You deserve compassionate care after an injury. You deserve an Advocate.