Bites and Stings: The Worst Insects in the US

Cow killer

Welcome to peak season for bites and stings. The summer months of July and August each send about 170,000 Americans to emergency rooms for treatment of bug bite and insect sting emergencies.

According to a study published by the Southern Medical Journal in May 2020, an average of 1.2 million Americans a year needed emergency treatment for bug bites and stings. These bites cost an estimated $5.7 billion in health care costs and lost wages.

But which bugs are worst? And where are particular bugs the worst?

To answer the questions, Pest Gnome evaluated biting and stinging pests in four ways. We looked for:

  • The most common pests. Our definition of pests is broad, including spiders, scorpions, and insects. If it’s not a mammal and not a reptile, we counted it.
  • Which ones cause the most trips to the doctor.
  • Which kill the most people.
  • Whose bite is most painful.

We tabulated the results for each pest and each state. Here’s what we found.

10 Worst Biting, Stinging Insects and Pests in the United States

1. Bees

Photo Credit: Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services, / Wikimedia Commons / CC BY 3.0

Bees bring honey, pollinate plants and buzz sweetly. They’re also the most deadly insect in the United States, by far. Allergic reactions to their stings kill about 62 people a year in the U.S. and send thousands more to emergency rooms. Like cars, peanut butter, or German shepherds, they’re everywhere, and as with anything that common, accidents happen.

  • How common: All 50 states, with 4,000 native species
  • ER visits caused: High
  • Pain/damage: 1-4 on 4-point scale

2. Mosquitoes

picture of a mosquito sitting on a skin
Photo Credit: PongMoji / Canva Pro / License

Worldwide, mosquitoes kill more people than any other insect. Mosquitoes spread malaria, dengue and yellow fever. In the United States, they are widespread but less-deadly. Centuries of eradication efforts and modern medicine have turned them into “just” a persistent, disease-bearing pest. Mosquitoes deserve respect, and every slap we can spare.

  • How common: All 50 states
  • ER visits caused: Medium
  • Pain/damage: 1-4 on 4-point scale

3. Ticks

tick on a hand
Photo Credit: John Tann / Flickr / CC BY 2.0

Sneaky, annoying and persistent. That’s the life of a tick. Six species feast on human blood, and they’re particularly nasty in the Northeast (hello Lyme disease) and in Colorado (nice to meet you, Rocky Mountain spotted fever). Tick-borne diseases have doubled in recent years.

  • How common: Populations of human-biting ticks live in 49 states. Enjoy, Alaska.
  • ER visits caused: High
  • Pain/damage: 1-3 on a 4-point scale

4. Yellow jackets, wasps, hornets

Photo Credit: Sue Thompson / Flickr / CC BY-ND 2.0

Stings from these larger flying insects are rarer than those of bees, but boy, can they hurt. Two in particular, the tarantula hawk wasp and cow killer hornet, have some of the most painful bites of all insects in North America.

Bug researcher Justin Schmidt described the tarantula hawk’s bite as “blinding, fierce, shockingly electric. A running hair dryer has just been dropped into your bubble bath.” The number of United States deaths caused by hornet, wasp or bee stings ticked up each year from 2012 to 2017.

  • How common: All 50 states, with the tarantula hawk in 17
  • ER visits caused: Medium
  • Pain/damage: 2-4 on a scale of 4

5. Kissing bug

Photo Credit: gailhampshire / Wikimedia Commons / CC BY 2.0

This is the grossest bug on our list. Attracted by carbon dioxide, this blood-sucking insect bites people on the face, then defecates. If the feces enter your body through the eyes, nose, or mouth, it can spread Chagas disease. The U.S. Centers for Disease Control and Prevention calls Chagas a “neglected parasitic infection” that is carried by an estimated 300,000 people, and up to 30% could years later develop life-threatening health problems, including heart disease.

  • How common: 28 states
  • ER visits caused: Few.
  • Pain/damage: 2-4 on a 4-point scale

6. Black widow spiders

Photo Credit: Chuck Evans (mcevan) / Wikimedia Commons / CC BY 2.5

Distinctive with their red hourglass, the black widow is considered the most-venomous spider in North America, with poison stronger than a rattlesnake’s. Black widows prefer dry, dark shelters and are not aggressive, but when they do bite it is painful and occasionally fatal if untreated. Females are about 1.5 inches long — twice the size of males, who sometimes get eaten after mating.

  • How common: 50 states
  • ER visits caused: Rare.
  • Pain/damage: 2-3 on 4-point scale

7. Bed bugs

Photo Credit: Picryl

Bed bugs have made a dramatic comeback after nearly being eliminated in the 20th century. We travel more, taking these opportunistic hitchhikers with us. And the once-common pesticide DDT, while effective, was so toxic it had to be banned. So, if we’re not careful, we will share our sleeping quarters with these quarter-inch bloodsuckers.

  • How common: 50 states.
  • ER visits caused: Medium
  • Pain/damage: 2 on a scale of 4

8. Brown recluse spiders

Photo Credit: PeteMuller / Canva Pro / License

These small, brown spiders live up to their name. Brown recluse spiders are shy inhabitants of the South and Midwest that rarely come into view and bite only in desperation. You may not even feel a brown recluse when it bites you. But oh, the damage later. A brown recluse’s venom causes necrosis — injuring and killing nearby tissue. Fatalities, however, are very rare.

  • How common: 23 states in the South and Midwest
  • ER visits caused: Low
  • Pain/damage: 1-3 on a 4-point scale

9. Ants

Photo Credit: Egor Kamelev / Pexels

While ants disrupt picnics, they’re mostly benign. The exception: imported red fire ants. Since arriving in the 1930s, fire ants have spread far and bit many. Legend has it they use a pheromone signal to swarm and all bite at once. Though the legend isn’t supported by science, tell that to a picnicker whose legs are covered with painful welts.

  • How common: All 50 states, with imported red fire ants in 13 Southern states
  • ER visits caused: Medium
  • Pain/damage: 1-3 on 4-point scale

10. Scorpions

Photo Credit: Doug Letterman / Flickr / CC BY 2.0

At the rear of our top 10 is the pest with a deadly backside: the scorpion. Rarely lethal, but a scorpion’s tail packs a painful venom. Arizonans and Nevadans know to shake their shoes in the morning.

  • How common: Scorpions can be found in 30 states, but are commonplace in only the Southwest. The Arizona bark scorpion, which roams the Sonoran desert, is a particularly painful pest.
  • ER visits caused: Medium
  • Pain/damage: 2 on 4-point scale

State by State List: Which Pests Are Worst in Each State?

Bugs aren’t spread evenly. In the South, ants — specifically Solenopsis invicta, the imported red fire ant — have blistered millions of legs with their fierce bites. They invaded the United States via a cargo ship that landed in Mobile, Alabama, in the 1930s, and since have spread to a dozen Southern states. In terms of bother, they have surpassed the traditional pest, the mosquito, in how often they are cursed (and cause trips to the emergency room).

Ticks, meanwhile, are mainly a scourge in the Northeast, where they carry Lyme disease and send thousands of people to emergency rooms each year.

We analyzed bugs for every state, and added one more criterion — online searches. Where there was a close call between worst stinging and biting pest for a state, the intensity of search activity on Google broke the tie.

baddest bugs by state graphic

Insect Bites and What They Do

Any type of bug bite can cause immediate damage via the venomous stinger. Pain is usually confined to the affected area and are not a medical emergency. Also, some bites and stings can cause a severe allergic reaction (anaphylaxis) that causes difficulty breathing and requires medical attention. And beyond immediate severe reactions, some bug bites and stings carry diseases that can be fatal — sometimes years later.

Data on insect bites, like some caterpillars, are fuzzy. Often, we don’t know what bit us. We come in the house after gardening or wake up in the morning and go “ow.” According to the Southern Medical Journal, about half of all insect bites in the U.S. that led to medical care came from unidentified insects.

But from the ones that could be identified, here’s some science. These are the most-typical stings and bites, what they cause, and their typical treatment.

Bee stings

If you look around our LawnStarter sister site site, you’ll see we love bees! Bees pollinate our gardens. They make honey. And if you have a flowering bush, you probably enjoy the hum of their wings. But they’re like the peanut butter or German shepherd of the insect world: extremely common. When something’s this common, bad things happen occasionally.

Some people are allergic to bees, so they statistically lead in the number of insect stings and deaths in the U.S. Personal note to bees: You’re still welcome in my garden.

Annual number of bee bites in the U.S. requiring emergency medical treatment: 147,699

Treatment: Take tweezers to the venom sac and pull it out if it is still present. The stinger can continue to pump even after the bee has left it behind. Apply an ice pack, and consider taking over-the-counter pain medicine. Because bee venom contains histamines, an antihistamine may decrease swelling. Watch for allergic reactions and seek medical help if needed.

Hornet, yellow jacket and wasp stings

Hornet stings are among the most painful insect stings in the United States. For example, researcher Justin Schmidt describes the pain of the cow killer wasp as “Explosive and long-lasting, you sound insane as you scream” and compares the feeling to “hot oil from the deep fryer spilling over your entire hand.”

Annual number of hornet, yellow jacket, and wasp stings in the U.S. requiring emergency medical treatment: 37,460

Treatment: Stay calm, but leave the area. Unlike most bees — hornets, yellow jackets, and wasps may sting repeatedly, and some may swarm. Treatment is the same for a bee sting, but because the amount of venom is higher, the skin reaction and even flu-like symptoms may result.

Here’s what to do: Remove the venom sac with tweezers or the edge of a credit card. Careful! If you squeeze the sac, it could release more poison. Wheezing or trouble breathing could signal an allergic reaction requiring immediate attention.

Spider bites

Black widow spider bites: These bites cause sharp, immediate pain as the spider injects its venom, which is more potent than a rattlesnake’s, but fortunately, injected in smaller quantities.

Annual number of black widow spider bites in the U.S requiring emergency medical treatment: 1,371. That puts a black widow bite in the extremely rare category. Serious black widow spider bites are more common than a shark attack but less common than being struck by lightning.

Treatment:  A black widow spider bite can escalate quickly. If you’re lucky, you’ll have only swelling and redness at the site of the bite. For others, within 30 to 60 minutes, more severe symptoms will appear, including spasms that start at the site of the bite and then spread. Seek medical advice immediately if you suspect a black widow has bitten you.

Brown recluse spider bites: If you happen across a brown recluse and it bites you, expect some pain and soreness at the point where it chomped you. You’ll be fine. Take some pain relievers. Statistically, this is slightly more likely to happen to you than a black widow bite. But brown recluse bites that need medical intervention are also very rare cases.

Annual number of brown recluse spider bites in the U.S. requiring emergency medical treatment: 1,734

Treatment: Cleanse. If the bite is on an arm or leg, keep it elevated. Apply lotion. Monitor for allergic reaction.

Other spider bites: The black widow and the brown recluse get the most attention, but other arachnids bite, too — and much more often.

Annual number of other spider bites in the U.S. requiring emergency medical treatment: 117,275

TreatmentStart with the same regimen as you would if it was a poisonous spider since you often won’t know what it was that bit you. Clean, elevate the limb, apply a cold compress. Watch for an allergic reaction.

Flea bites

There are dog flea species and cat flea species, but fleas are not fussy. They’ll bite any mammal, including you, to get the blood they need to continue their life cycle. Fleas will lurk in your lawn, waiting to get fed.

Annual number of flea bites in the U.S. requiring emergency medical treatment: 5,058

Treatment: If you see a small red bump, especially if it has a red “halo” around it, it’s likely to be a flea bite.  Clean and treat with lotion. It’s hard, but avoid scratching, which can cause a secondary infection.

Bed bug bites

You may not immediately notice a bed bug infestation. But if you wake up with fresh sores, your bed (or couch or easy chair) may contain bed bugs.

Annual number of bed bug bites in U.S. requiring emergency medical treatment: 23,246

Treatment: Pack up and move. If that’s not an option, get ready for a fight. Bed bugs are a tough opponent.

Mosquito bites

Malaria, Zika, West Nile virus, and dengue fever are among the nasty diseases that mosquitoes carry. Deet is a time-proven, effective insect repellent, but in summer, a few red marks from mosquito bites are inevitable.

Annual number of mosquito bites in U.S. requiring emergency medical treatment: 20,607

Treatment: A lotion containing calamine may help the itchiness. You may also get relief from an over-the-counter lotion containing 1% hydrocortisone. As with many insect bites, a cold compress may help.

Ant bites

Ordinary ants just crash your picnic or backyard party. But starting in the 1930s, a new and much more painful biting ant got off a boat in Mobile, Alabama, and started spreading through the Southern states. The red imported fire ant is a resilient enemy. Think you can turn a hose on them? They’ll turn into a giant floating ball of nastiness.

Annual number of ant bites in U.S. requiring emergency medical treatment: 11,476

Treatment: Don’t scratch those blisters. Treat with a cold compress, elevate, take antihistamines and pain relievers.

Tick bites

In the Northeast, Lyme disease carried by ticks is a serious health menace. Head out to Colorado, and ticks spread Rocky Mountain spotted fever. The Centers for Disease Control and Prevention (CDC) lists 16 diseases that ticks spread.

Annual number of tick bites in the U.S. requiring emergency medical treatment: 95,379

Treatment: Job No. 1: Remove the tick. All of it. Right away. Use sanitized tweezers. Forget the old legend about using a newly extinguished match. Most tick bites cause a bit of redness, but if you start to see a spreading skin rash, that could be a sign of Lyme disease.

Kissing bug

While not common, the damage left behind by a kissing bug bite can be among the most severe — and sneaky. The immediate symptoms may be mild to severe swelling. But you may not know for years the full impact. That’s because kissing bugs pass Chagas disease, a potentially deadly disease that may not show up for a decade or more.

Annual number of kissing bug bites in the U.S. requiring emergency medical treatment: 673

Treatment: Wash, wash, wash to decrease the chance of infection. See a physician if you think you’ve been bitten. There are tests that can determine whether the Chagas disease virus was passed.


A healthy adult can withstand the bite of a scorpion — at least, the common types found in the Southwest. (If you’ve been walking around in the Israeli desert and a straw-yellow scorpion bit you, that’s another matter. That’s deathstalker scorpion territory, and you’re probably not reading this because you already died.)

Annual number of scorpion bites/stings in the U.S. requiring emergency medical treatment: 7,918

Treatment: Treat a scorpion’s sting as you would other bites, with an ice pack, pain relievers and, since you’re probably in a state that borders Mexico, a shot of tequila, if you’re so inclined. But for children, older adults, and those with medical difficulties, it may be serious. Monitor for breathing difficulties, sweating, and nausea, and get to a doctor right away if those symptoms occur.

Fly bites

The big culprit here? The horsefly. It causes most of the emergency room visits, and horse fly bites really hurt. Beekeepers report they’d rather be stung by their bees than get a horsefly bite. Flies are seasonal swarming pests that can ruin a picnic or day at the beach in a hurry, but mostly just annoy. The exception is Wisconsin, where summer infestations of deerflies and horseflies make them the worst Wisconsin pest.

Annual number of fly bites in the U.S. requiring emergency medical treatment: 1,146

Treatment: Clean the wound. Take cover. Get a flyswatter. Use natural repellents to deter flies.


To determine the Top 10 bugs list and the worst stinging and biting pests in each state, we gathered and compared available data on the incidence of non-mammal, non-reptilian deaths and emergency room visits, and a pain-of-sting index. We added the number of states in which a pest is found to determine how widespread it is, and added in the volume of searches on Google Trends across the 50 states and the District of Columbia for each pest.

Sources: The Centers for Disease Control and Prevention (CDC), Southern Medical JournalNational Institutes of Health, the U.S. Census Bureau, Google Trends,, “Schmidt Index” of bug bite pain from Justin O. Schmidt’s 2016 book “The Sting of the Wild.

Main Photo Credit:Pixabay

Daniel Ray

Daniel Ray is an award-winning writer and editor who previously was editor in chief of the personal finance websites and, but with 30 years of gardening experience, he's well qualified to help consumers grow a different kind of green.