Tennessee is home to several bugs that can cause serious harm, from venomous spiders and disease-carrying ticks to stinging caterpillars that most people don’t even know exist. The biggest threats aren’t always the most obvious ones. Ticks transmit potentially life-threatening infections, spiders can cause wounds that take months to heal, and a single lone star tick bite can permanently change what you’re able to eat. Here’s what to watch for and how to protect yourself.
Brown Recluse Spiders
Tennessee is one of 16 states where brown recluse spiders are established, and encounters are common. These chocolate-brown spiders are small, with bodies only about 9 millimeters long, and they carry a distinctive violin-shaped marking on the area behind their head. Unlike most spiders, they have six eyes arranged in three pairs rather than the typical eight. They prefer warm, dry spots: gaps under rocks and dead bark outdoors, and cracks in walls, storage boxes, and cluttered closets indoors.
A brown recluse bite often isn’t painful at first. Within three to eight hours, the area becomes red, sensitive, and feels like it’s burning. It may develop a bullseye appearance or turn bluish. If the spider injected only a small amount of venom, discomfort typically fades within a few days. In more serious bites, an ulcer forms at the site within three to five days and the surrounding skin begins breaking down over one to two weeks. The wound can take several months to fully heal, eventually forming a thick black scab around the three-week mark. Some bites also cause body-wide symptoms like fever, chills, vomiting, and muscle pain in the abdomen, back, and legs.
If you’re bitten, wash the area with soap and water immediately, apply a cold compress, and elevate the bite if possible. Severe bites, particularly those with spreading redness or ulceration, need medical attention. Antibiotics are often prescribed to prevent secondary infection.
Black Widow Spiders
Black widows live throughout Tennessee, typically in woodpiles, sheds, garages, and undisturbed outdoor structures. The females are the dangerous ones: glossy black with a red hourglass marking on the underside of the abdomen. Their venom is a neurotoxin that affects the nervous system, causing intense muscle pain and cramping that can spread from the bite site across the body. Most bites happen when someone reaches into a space where a spider is hiding, like putting on a shoe stored in a garage or moving firewood. Bites are rarely fatal in healthy adults but can be serious for young children and elderly people.
Ticks and Rocky Mountain Spotted Fever
Ticks are arguably the most dangerous bugs in Tennessee because of the diseases they carry. The state reported 4,352 probable and confirmed cases of spotted fever rickettsiosis (the group of illnesses that includes Rocky Mountain spotted fever) between 2013 and 2023. Some Tennessee counties see more than 26 cases per 100,000 residents per year.
Peak transmission runs from early spring through late summer, with cases concentrated between May and September. Early symptoms, fever, headache, nausea, muscle pain, and a rash of red splotches or pinpoint dots, look a lot like the flu. That resemblance is what makes it dangerous. Left untreated, Rocky Mountain spotted fever can rapidly progress to a life-threatening illness. If you develop a fever after a tick bite, your doctor will typically start antibiotics before test results even come back, because early treatment is critical.
Lyme Disease in Tennessee
Lyme disease is less common here than in the Northeast, but it’s rising. Tennessee reported 39 cases in 2023, an 18% jump from the prior year, and 94% of cases over the past decade occurred in the Middle and Eastern parts of the state. The blacklegged tick (also called the deer tick) is the carrier.
Symptoms typically appear 3 to 30 days after a bite: fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes. The classic bullseye rash is a telltale sign, but not everyone develops it. Cases peak from June through August. If you find a tick that may have been attached for 36 hours or more, or you develop flu-like symptoms or joint pain in the days to months following a bite, get evaluated promptly.
Lone Star Ticks and Alpha-Gal Syndrome
The lone star tick is extremely common in Tennessee and carries a unique risk that most people outside the Southeast have never heard of. Its saliva contains a sugar molecule called alpha-gal, which is also found in red meat. When the tick bites you, it can trigger your immune system to produce antibodies against alpha-gal. The result: you develop an allergic reaction every time you eat beef, pork, lamb, or other mammalian meat, sometimes for the rest of your life.
Tennessee is one of five states with the highest rates of alpha-gal antibodies. A CDC study of blood donor samples from 2024 to 2025 found that more than 21% of Tennessee adults tested positive for these antibodies, and across the five highest-prevalence states, roughly one in four adults carried them. Not everyone with the antibodies develops full-blown allergic symptoms, but those who do can experience hives, stomach cramps, nausea, and in some cases anaphylaxis, hours after eating red meat. The delayed reaction (often 3 to 6 hours after a meal) makes it tricky to connect to food.
Yellowjackets, Wasps, and Hornets
Tennessee’s warm summers bring heavy activity from yellowjackets, paper wasps, and hornets. These insects are closely related and all build paper-like nests, making them hard to tell apart. Yellowjackets are the most aggressive of the group and are responsible for the majority of stinging incidents, especially in late summer when their colonies are large and food competition is fierce. Paper wasps are comparatively less aggressive but will sting when their nest is disturbed.
For most people, a sting causes temporary pain, redness, and swelling. But about 3% of adults and up to 1% of children experience a systemic allergic reaction, meaning the response spreads beyond the sting site. Warning signs of a dangerous reaction include hives or rash on other parts of your body, swelling of the lips, tongue, or throat, difficulty breathing or swallowing, dizziness, and loss of consciousness. This is anaphylaxis, and it requires emergency treatment with epinephrine immediately.
Mosquitoes and La Crosse Virus
Tennessee mosquitoes carry several viruses, but La Crosse encephalitis is the standout concern, particularly in the eastern part of the state. Each summer, mosquitoes in East Tennessee transmit La Crosse virus to humans. Infections primarily strike children under 16. Many cases are asymptomatic, but when symptoms appear, they include fever, headache, nausea, vomiting, and fatigue lasting up to 15 days.
In severe cases, the virus crosses into the brain and causes encephalitis, leading to seizures, coma, and paralysis. Long-term cognitive problems can follow, and in rare instances the infection is fatal. West Nile virus is also present in Tennessee, though less geographically concentrated than La Crosse. Mosquito activity peaks from late spring through early fall, with the highest risk during humid summer evenings.
Venomous Caterpillars
Several stinging caterpillar species live in Tennessee, and brushing against one can be surprisingly painful. These caterpillars have hollow, quill-like hairs connected to venom sacs. When you touch them, the hairs pierce your skin and release poison, causing reactions that range from mild itching to intense pain, swelling, blistering, and skin irritation.
The puss caterpillar is the worst offender. It looks harmless, covered in a dense coat of soft brown hair that makes it resemble a tiny toupee. But hidden beneath those long hairs are short, venomous spines that deliver one of the most painful caterpillar stings in North America. The larger the caterpillar, the worse the sting. The saddleback caterpillar, a green caterpillar with a distinctive brown “saddle” marking on its back, also causes severe stings. Other stinging species found in the state include the io moth caterpillar (bright green with branched yellow spines), the buck moth caterpillar (dark with yellow spots and black spines), and the hag moth caterpillar, which looks like a dried leaf but is armed with stinging hairs on its fleshy lobes.
Most caterpillar stings don’t require medical attention, but the pain can be intense for several hours. Applying tape to the area and peeling it off can help remove embedded spines. Ice and over-the-counter pain relief generally handle the rest.
When a Bug Bite Needs Emergency Care
Most bites and stings in Tennessee are painful but not dangerous. The situations that demand immediate attention fall into two categories: severe allergic reactions and signs of spreading infection. For allergic reactions, watch for hives or rash appearing away from the bite site, swelling of your lips, tongue, or throat, trouble breathing or swallowing, abdominal cramping with nausea or vomiting, and dizziness or confusion. Any of these after a sting or bite means you need emergency care immediately.
For infections, the red flags are a fever developing after a bite, pus at the site, red streaks on your skin extending outward from the bite, and worsening redness, pain, or warmth around the area. After a tick bite specifically, a bullseye rash, flu-like symptoms, neck pain, or widespread joint pain in the days to months afterward all warrant a medical visit. The common thread with tick-borne illness in Tennessee is that early treatment with antibiotics makes a dramatic difference in outcomes, so don’t wait to see if symptoms resolve on their own.