Dangerous Bugs in the US You Should Know
These bugs can cause medically significant bites, stings or disease. This guide covers 12 of them.
Quick list
How to narrow it down
Narrow it down with three quick checks. Count the legs: insects have six, spiders and ticks have eight, and centipedes and millipedes have many more. Check for wings, even folded ones. Then compare size against a coin: a US penny is 19 mm across. Our bug identifier tool does this filtering for you.
The 12 bugs
American Dog Tick
American Dog TickDermacentor variabilisA brown tick with ornate white-gray markings on its shield, common along trails, roadsides and grassy fields. It readily feeds on dogs and people.
Tell-tale sign: Brown body with silvery-white mottling on the shield. Risk: American dog ticks can transmit Rocky Mountain spotted fever and tularemia.
Arizona Bark Scorpion
Arizona Bark ScorpionCentruroides sculpturatusA slender, light tan scorpion of the desert Southwest and the most venomous scorpion in North America. It climbs walls and ceilings and often hides in shoes, bedding and clothing.
Tell-tale sign: Thin, light yellowish-tan body and slender pincers. Risk: Bark scorpion stings cause severe pain and numbness and can be dangerous for young children and older adults; call Poison Control at 1-800-222-1222 after a sting.
Bald-Faced Hornet
Bald-Faced HornetDolichovespula maculataA black wasp with ivory-white markings on its face and the tip of its abdomen. It builds large, gray, football-shaped paper nests in trees, shrubs and under eaves.
Tell-tale sign: Black body with a white face and white tail markings. Risk: Bald-faced hornets deliver painful stings and attack in numbers when their nest is disturbed.
Black Widow Spider
Black Widow SpiderLatrodectus mactansA shiny black spider with a red hourglass on the underside of its round abdomen. It builds messy, tangled webs in woodpiles, sheds, meter boxes and outdoor furniture.
Tell-tale sign: Glossy black, globe-shaped abdomen. Risk: Females have venom that can cause severe muscle pain and cramps; seek medical care after a bite.
Blacklegged Tick
Blacklegged TickIxodes scapularisAlso called the deer tick, a small tick with a dark shield and, in adult females, a reddish-orange rear body. It waits on grass and brush to latch onto passing people and animals.
Tell-tale sign: Dark black legs and shield. Risk: Blacklegged ticks transmit Lyme disease, anaplasmosis and babesiosis; remove attached ticks promptly.
Brown Recluse Spider
Brown Recluse SpiderLoxosceles reclusaA tan to brown spider with a dark violin-shaped mark on its back and only six eyes. It hides in boxes, closets and unused clothing in the south-central US.
Tell-tale sign: Dark violin-shaped mark pointing toward the abdomen. Risk: Most bites are mild, but some cause a spreading wound that needs medical care.
European Hornet
European HornetVespa crabroThe only true hornet established in North America, a large brown-and-yellow wasp that nests in hollow trees, barns and wall voids. It often flies at night and is attracted to lights.
Tell-tale sign: Large wasp with a reddish-brown head and thorax. Risk: European hornet stings are very painful, and colonies defend their nest, though workers are less aggressive away from it.
Kissing Bug
Kissing BugTriatoma sanguisugaA cone-nosed assassin bug with orange-red markings around the edge of its flat abdomen. It feeds on the blood of animals and people, sometimes biting near the face at night.
Tell-tale sign: Elongated, cone-shaped head. Risk: Kissing bugs can carry the parasite that causes Chagas disease; save the bug and contact your health department if you are bitten.
Lone Star Tick
Lone Star TickAmblyomma americanumAn aggressive, reddish-brown tick of the Southeast and East; adult females have a single white spot on the back. All life stages bite people.
Tell-tale sign: Single white dot on the back of adult females. Risk: Lone star tick bites are linked to ehrlichiosis and alpha-gal syndrome, a red meat allergy.
Mosquito
MosquitoCulicidae (e.g. Aedes albopictus)A small, slender fly whose females bite to take blood for egg production. The Asian tiger mosquito is black with white stripes and bites aggressively during the day.
Tell-tale sign: Long, needle-like mouthpart (proboscis). Risk: Mosquito bites itch and, depending on the region, can transmit West Nile, dengue and other viruses.
Red Imported Fire Ant
Red Imported Fire AntSolenopsis invictaA small, aggressive reddish-brown ant that builds dome-shaped mounds of loose soil in sunny lawns and fields across the southern US. When disturbed, workers swarm and sting repeatedly.
Tell-tale sign: Mixed sizes of copper-red workers in one colony. Risk: Fire ant stings burn, form white pustules, and can cause severe allergic reactions in sensitive people.
Yellowjacket
YellowjacketVespula maculifronsA sleek, bright yellow-and-black wasp that nests underground or in wall voids. Late-summer workers scavenge for sweets and meat and are drawn to picnics and trash cans.
Tell-tale sign: Smooth, shiny yellow and black body with little hair. Risk: Yellowjackets sting repeatedly and defend nests aggressively; multiple stings or an allergy can be dangerous.
Which ones should you worry about?
12 of the 12 bugs in this guide can bite or sting. The ones to take seriously are American dog tick, Arizona bark scorpion, bald-faced hornet, black widow spider, blacklegged tick, brown recluse spider, European hornet, kissing bug, lone star tick, mosquito, red imported fire ant and yellowjacket. The rest are harmless or simply a nuisance.
Comparison at a glance
| American Dog Tick | Arizona Bark Scorpion | Bald-Faced Hornet | |
|---|---|---|---|
| Group | Ticks, Mites & Other Arachnids | Ticks, Mites & Other Arachnids | Bees & Wasps |
| Scientific name | Dermacentor variabilis | Centruroides sculpturatus | Dolichovespula maculata |
| Size | 3–5 mm | 50–80 mm | 15–20 mm |
| Colors | Brown, White and Gray | Tan and Yellow | Black and White |
| Legs | 8 legs | 8 legs | 6 legs |
| Wings | No | No | Yes |
| Bites or stings | Bites | Stings | Stings |
| Risk | Health risk | Health risk | Health risk |
| Key feature | Brown body with silvery-white mottling on the shield | Thin, light yellowish-tan body and slender pincers | Black body with a white face and white tail markings |
Frequently asked questions
What is the most common one?
Among the bugs in this guide, the American dog tick and Arizona bark scorpion are the ones people ask about most.
Which of these are dangerous?
American Dog Tick, Arizona Bark Scorpion, Bald-Faced Hornet, Black Widow Spider, Blacklegged Tick, Brown Recluse Spider, European Hornet, Kissing Bug, Lone Star Tick, Mosquito, Red Imported Fire Ant and Yellowjacket can be medically significant.
How can I identify a bug I found?
Use the free bug identifier tool: choose the number of legs, wings, main color, size and where you found it, and it will list the closest matches.