Tick Season in Illinois Explained: Active Months, High-Risk Areas, and Bite Prevention

Tick season in Illinois is longer and more widespread than many residents realize. While most people associate tick activity with summer camping trips or hikes through the woods, ticks in this state can be active from early spring all the way through late fall — and sometimes even on mild winter days.

Whether you spend time outdoors for work, recreation, or simply walking your dog around the neighborhood, understanding when ticks are most active, where they live, and how to protect yourself can make a meaningful difference for your health. This guide walks you through everything you need to know to navigate tick season in Illinois with confidence.

When Is Tick Season in Illinois?

Tick activity in Illinois typically stretches from early spring through November, with two especially active periods: April through June and again from September into late fall. That’s a much longer window than many people expect, and it means you shouldn’t let your guard down just because summer is winding down.

Ticks become active as soon as temperatures are consistently above freezing, according to public health officials. Ticks can be active on winter days when the ground temperatures are about 45°F. In practical terms, this means that even a warm January afternoon in Illinois could bring ticks out of dormancy.

Adult ticks are most active in April, May, and June, according to the Illinois Department of Public Health. While tick season continues through the summer into mid-fall, the life cycle of different tick species varies and plays a role in when they are most likely to be found on humans.

Key Insight: Illinois has two peak tick periods — spring (April–June) and early fall (September–November). Planning outdoor activities? These are the months to be most vigilant about tick checks.

The nymph stage of the blacklegged tick is particularly concerning during the warmer months. Nymphs are tiny — roughly the size of a poppy seed — which makes them easy to miss during a body check. Avoid wooded and grassy areas where ticks are commonly found, especially during peak tick season, which typically runs from spring through fall but can occur whenever temperatures are above freezing.

Types of Ticks Found in Illinois

Although at least 15 species of ticks occur in Illinois, only a few of these ticks are likely to be encountered by people: the American dog tick, lone star tick, blacklegged (deer) tick, brown dog tick, and winter tick. Knowing how to identify each one can help you understand your risk level and what steps to take if you find one attached to your skin.

American Dog Tick (Wood Tick)

The American dog tick, also known as the wood tick, is the most common tick in Illinois. These ticks are red in color and usually 3/16 of an inch long, with well-fed females growing as large as 1/2 an inch in length. Females also have a small silver spot behind their heads.

In Illinois, adults are most active in April, May, and June. By September, the adults are inactive and are rarely observed. Their preferred habitat includes wooded areas, forest and field edges, overgrown abandoned lots, fallow fields, roadsides, and grassy edges of hiking trails. They are considered well-distributed throughout Illinois.

Blacklegged Tick (Deer Tick)

Known as the deer tick, this tick is reddish-brown in color and grows to 1/8 of an inch in length. Deer ticks are active from spring through the fall, depending on the life stage. The deer tick is common in wooded areas in Michigan, Minnesota, and Wisconsin and has been making its way into northern Illinois in recent years.

The deer tick has been found sporadically in many Illinois counties. However, in recent years it has been common only in limited areas, mostly in northern Illinois. Approximately 40% of Illinois deer ticks are positive carriers of Lyme disease, according to the Illinois Natural History Survey (INHS) Medical Entomology Lab.

Important Note: If you’re traveling to Wisconsin, Minnesota, or Michigan for hunting or recreation, be aware that there is a much higher prevalence of Lyme disease in those areas, as well as across the northeastern United States. Take extra precautions before and after your trip.

Lone Star Tick

The lone star tick is primarily found in the southern half of Illinois, although it can occasionally be found further north. Larvae, nymphs, and adults will feed on a variety of warm-blooded hosts, including people. The lone star tick is most active from April through the end of July.

The adult female is easy to identify: the adult female has a white spot in the middle of her back. Lone star tick populations are most dense in southern and central Illinois, but populations are increasing northwards and are expected to become common throughout the state.

Brown Dog Tick

The brown dog tick, also known as the kennel tick, is found throughout most of the United States. This tick feeds on dogs but rarely bites people. Unlike other species of ticks, its life cycle allows it to survive and develop indoors. The brown dog tick is found primarily in kennels or homes with dogs where it may be found hiding in cracks, behind radiators, under rugs and furniture, and on draperies and walls.

While it poses minimal risk to humans, it’s worth knowing about if you have dogs that visit kennels or grooming facilities. You can learn more about natural tick predators that help keep tick populations in check around your property.

Tick Species	Primary Region in Illinois	Peak Active Months	Key Identifier
American Dog Tick	Statewide	April – June	Silver spot (female); reddish-brown
Blacklegged (Deer) Tick	Northern Illinois	Spring – Fall	Reddish-brown; 1/8 inch; dark legs
Lone Star Tick	Southern & Central Illinois	April – July	White dot on female’s back
Brown Dog Tick	Statewide (mostly indoors)	Year-round	Reddish-brown; narrow body

Tick-Borne Diseases in Illinois

Ticks in Illinois are known to carry a range of diseases that can pose serious health risks to humans. Lyme disease is one of the most common tick-borne illnesses in the state, caused by the bite of a blacklegged tick infected with the bacteria Borrelia burgdorferi.

Not every tick carries these diseases, so not every tick bite will make you sick. However, these illnesses are significant and will require immediate medical attention at the first sign of symptoms. Here is a closer look at the diseases you need to know about.

Lyme Disease

Lyme disease is a bacterial infection carried by ticks found in the northeastern and north-central United States, including Illinois. The most noticeable symptom is a red bull’s-eye rash appearing at the bite mark within days of being infected. Flu-like symptoms such as fever, chills, nausea, and aching joints may occur and reoccur for several weeks. If not treated, irregularities in heartbeat, nervous system problems, and arthritis may develop. Antibiotics are effective in controlling this disease if treatment is started early.

You can also read our detailed article on tick-borne encephalitis to understand how tick-borne viruses can affect the nervous system.

Rocky Mountain Spotted Fever

Some tick-borne illnesses can be life-threatening. Rocky Mountain Spotted Fever is particularly dangerous and may cause death as quickly as five days after symptom onset. The American dog tick can transmit Rocky Mountain spotted fever, tularemia, and possibly ehrlichiosis to humans. With 350 cases, southern Illinois has a high incidence of Rocky Mountain spotted fever group rickettsiosis, which is transmitted by the dog tick.

Ehrlichiosis

Ehrlichiosis is a bacterial illness caused by certain strains of the Ehrlichia bacteria, and it’s transmitted to humans through tick bites. The disease can impact the body’s white blood cells, leading to a range of symptoms that can be mild to severe. The bacteria also affects the immune system and sometimes causes life-threatening complications.

In Illinois, ehrlichiosis is most commonly spread by the lone star tick. This tick species is found in many parts of the Midwest and is particularly abundant in southern and central Illinois, residing in wooded areas and tall grasses. As of October 2024, an Illinois Tick Surveillance Map from IDPH indicates that various species of Ehrlichia have been found in more than 25 counties in the state and counting.

Babesiosis

Other tick-borne diseases found in Illinois include coinfections such as anaplasma, babesia, and ehrlichia, all of which can result in flu-like symptoms and, if left untreated, may lead to severe complications. Babesiosis, transmitted by the blacklegged tick, infects red blood cells and can be especially dangerous for people with weakened immune systems or those who have had their spleen removed.

Alpha-Gal Syndrome

Cases of a meat allergy and an allergy to other mammalian products called alpha-gal syndrome are also on the rise. The life-threatening allergy comes from the bite of a lone star tick. Illinois ranks among the top 13 states with increasing incidence of alpha-gal syndrome, caused by the bite of the lone star tick. If you develop unexplained allergic reactions after eating red meat, mention any recent tick bites to your doctor.

Powassan Virus

Powassan is a tick-borne virus found in the Northeast and Great Lakes areas. This disease infects a patient’s nervous system, causing inflammation of the brain and meningitis. Unlike the bacterial infections listed above, Powassan has no known treatment. Symptoms include headaches, vomiting, confusion, difficulty speaking or walking, and seizures.

The IDPH recommends taking appropriate precautions to protect against all tick bites, even in the fall season, after an Illinois resident became seriously ill with Powassan.

Common Mistake: Many people assume that tick-borne illness symptoms are just the flu and wait it out. Because many of these diseases share similar symptoms, always mention recent outdoor exposure or a known tick bite to your healthcare provider so they can test appropriately.

High-Risk Areas and Habitats in Illinois

Understanding where ticks live in Illinois is one of the most effective tools you have for reducing your exposure. Ticks don’t wander randomly — they position themselves strategically to find a host.

Ticks wait for host animals from the tips of grasses and shrubs — not from trees. When brushed by a moving animal or person, they quickly let go of the vegetation and climb onto the host. Ticks can only crawl; they cannot fly or jump.

Natural Environments

Wooded areas are an ideal environment for ticks to live; the dense vegetation provides numerous hiding spots and hosts to feed on. Tall grasses and meadows are also common habitats for ticks, offering a combination of shade, moisture, and plenty of warm-blooded animals such as rodents and deer for meals.

The blacklegged tick is most common in secondary-growth forested areas with dense underbrush, especially along transitional zones such as vegetation or scrub along rivers and creeks near forest edges or between meadows and forest. These edge zones — where a wooded area meets a field or trail — are particularly high-risk spots.

Suburban and Urban Spaces

Ticks also reside in both suburban and urban areas — you may encounter them in local parks, beaches, walking and hiking paths, campgrounds, and more. Ultimately, ticks are adaptable and can thrive in a variety of habitats, making it crucial for individuals to become tick-aware and take precautions when outdoors.

Make sure the property around your home is unattractive to ticks. Because ticks are sensitive to dry conditions and do not thrive in short vegetation, they are seldom a problem in well-maintained lawns. Keeping your grass cut short and clearing leaf litter along fence lines can significantly reduce tick habitat around your home.

Regional Hotspots Across Illinois

Scientists analyzed the distribution of three potentially harmful tick species in Illinois and identified regions of the state with higher numbers of these ticks. The study found that the lone star tick is most prevalent in southern Illinois; the black-legged tick or deer tick is more common in northern and central Illinois; and the dog tick dominates the central and southern parts of the state.

With 350 cases, southern Illinois has a high incidence of Rocky Mountain spotted fever group rickettsiosis, which is transmitted by the dog tick. Pope and Hardin counties in southern Illinois, and Piatt and Moultrie in central Illinois were identified as hotspots for the dog tick.

Winnebago County is the highest at 71% of the ticks collected testing positive for Lyme disease. This is extremely alarming and puts urgency on the public to know how to protect themselves and their families from tick bites.

Pro Tip: The IDPH maintains an interactive Tick Surveillance Map that shows confirmed tick species and associated diseases by county. Check it before planning outdoor activities in a new area of the state.

If you enjoy hunting in Illinois — an activity that frequently takes you into prime tick habitat — it’s worth reviewing the goose hunting season in Illinois and pheasant hunting season in Illinois timelines, as these overlap significantly with peak tick activity periods in the state.

How to Protect Yourself, Children, and Pets During Tick Season in Illinois

The good news is that most tick bites — and the diseases they can transmit — are preventable with a few consistent habits. Wearing long clothing, using EPA-approved insect repellents, and doing thorough tick checks after spending time outdoors can significantly reduce your risk.

Protecting Yourself and Your Family

• Wear the right clothing: Wear long-sleeved shirts, long pants, and closed-toe shoes, and tuck your pants into your socks for an additional layer of protection.
• Use light colors: Wear light-colored clothing to make ticks easier to find.
• Apply repellent: Apply an EPA-registered insect repellent containing 20% DEET, picaridin, IR3535, or Oil of Lemon Eucalyptus according to label directions.
• Treat your clothing: The insecticide permethrin can be applied to clothing, or you can buy permethrin-treated clothing. Do not apply permethrin directly to your skin.
• Stay on trails: If hiking through wooded areas, remain on the center of the path and avoid brushing against vegetation or low leaves, as ticks could hide within them and latch on to you.
• Do full-body checks: Conduct full-body tick checks on family members — including underarms, ears, belly button, behind knees, between legs, waist, hair, and scalp — every two to three hours.
• Shower promptly: Bathe or shower within two hours after coming indoors.
• Dry your clothes: To kill ticks after being outdoors, put clothes in the dryer on high for 10 minutes, or one hour for damp clothes.

Protecting Children

Children are particularly vulnerable to tick bites because they tend to play in tall grass, roll around on the ground, and may not notice a small tick crawling on their skin. Always supervise children in the use of repellents. Apply repellent to your own hands first and then apply it to a child’s skin, avoiding the eyes, mouth, and hands.

The IDPH has created Pocket Cards, a Tick Defense Knowledge Check crossword puzzle, and other materials for school-aged children that make it fun for everyone in the family to learn how to protect themselves and their loved ones from tick-borne illnesses. These free resources are available on the IDPH website.

Protecting Pets

Free-roaming dogs and cats are much more likely to encounter ticks than those that are confined to the home or yard. It is possible for pets to bring in ticks from outside and transfer them to bedsheets and other places around the home.

• Ask your veterinarian about tick-preventive medications and products best suited for your pet’s size, species, and lifestyle.
• Consider whether a Lyme disease vaccine is appropriate for your dog, especially if you live in northern Illinois or travel to high-risk areas.
• Check your pet thoroughly after every outdoor outing, paying special attention to warm, moist areas of their bodies, including the scalp, ears, elbows, groin area, between the toes, and under the collar, tail, and legs.
• Make sure the property around your home is unattractive to ticks. Because ticks are sensitive to dry conditions and do not thrive in short vegetation, they are seldom a problem in well-maintained lawns. Keep your grass mowed and keep weeds cut.

For more detailed guidance on keeping your dog safe during tick season, visit our guide on preventing tick-borne diseases in your dog. You may also find it helpful to learn about how ticks reproduce so you understand the seasonal patterns behind tick population surges.

Pro Tip: Clean up items that attract rodents — which can carry ticks — such as spilled birdseed and hiding places like old wood piles. Reducing rodent activity around your yard is one of the most underrated ways to lower tick pressure near your home.

What to Do If You Find a Tick in Illinois

Finding a tick on yourself, your child, or your pet can be unsettling — but staying calm and acting quickly is the most important thing you can do. The sooner you remove the tick, the lower your risk of disease transmission.

Removing ticks within a 24-hour period reduces the risk of potential disease transmission. This is especially true for Lyme disease, which requires the blacklegged tick to be attached for at least 36 hours before the bacteria can be transmitted.

How to Remove a Tick Safely

1. Use fine-tipped tweezers: Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible. Slowly and steadily pull upward with even pressure.
2. Avoid these methods: Avoid twisting and squeezing the tick, smearing it with Vaseline or essential oils, or burning it. By manipulating the tick, you can cause it to regurgitate and/or increase its salivation — both of which can increase the risk of infection.
3. Clean the area: Once removed, clean the bite area and your hands thoroughly with rubbing alcohol or soap and water.
4. Save the tick: Save the tick in a container or plastic baggie with a moist cotton ball for potential identification or testing.
5. Monitor for symptoms: Keep tabs on any unusual symptoms, such as a distinctive rash or flu-like symptoms, and consult a healthcare professional if any concerns arise. Early detection and proper tick removal are crucial in preventing the spread of Lyme disease.

When to Seek Medical Attention

If you find a blacklegged tick on you that may have been attached for more than three days, seek medical attention to decide if you need an antibiotic to prevent Lyme disease. Anyone who has been exposed to wooded or high grassy areas and is experiencing symptoms — fever, fatigue, headache, and a circular rash — should see a healthcare provider immediately.

Tick-borne diseases can result in no symptoms, mild symptoms treatable at home, or severe infections requiring hospitalization. They can be extremely debilitating, life-threatening, and may result in long-term health problems or death. The diseases can be difficult to diagnose, so early recognition and treatment decrease the risk of serious complications.

Important Note: Folk remedies used in the past to remove ticks can be dangerous and even increase your chances of contracting a tick-transmitted disease. Do not use petroleum jelly, a hot match, nail polish, or other products to remove a tick.

Reporting Tick Bites and Tick-Borne Illness in Illinois

Reporting tick bites and suspected tick-borne illness isn’t just good for your own health — it helps public health officials track tick populations and disease spread across the state. Illinois has several programs designed to make this easy for residents.

Submitting a Tick for Identification

It is often helpful to keep the tick for species identification. Place the tick in rubbing alcohol or in a sealed bag or container to bring to your healthcare provider or local health department for submission to IDPH. A submission form can be found on the IDPH website.

To submit a tick for identification, put it into a leak-proof container with rubbing alcohol along with the date and location where the tick was encountered, and contact your local health department for assistance.

The I-TICK Surveillance Program

You can help monitor ticks in Illinois through the I-TICK program run by the University of Illinois College of Veterinary Medicine. The goal of the program is to find out more about where and when Illinois residents are encountering ticks. Through the I-TICK program, several hubs have been identified throughout the state, and these hubs serve as the distribution point for tick collection kits.

I-TICK relies on volunteers throughout Illinois, working with their local hubs, to collect ticks they find on themselves and to record data for the next five days, reporting this information and returning their collection kit within two weeks of the tick encounter. According to the university, ideal volunteer participants for the program are those who work outdoors regularly.

IDPH’s Tick Surveillance Map and Resources

IDPH has created an interactive Tick Surveillance Map that documents the counties in Illinois where the different tick species have been confirmed as well as the diseases they may carry. This is a valuable tool for anyone wanting to know the tick risk in their specific county before heading outdoors.

If you experience symptoms of a tick-borne illness after spending time outdoors, contact your healthcare provider promptly and be sure to mention any known tick exposure. Ehrlichiosis, for example, can be effectively treated with certain antibiotic medications if caught early. The same is true for Lyme disease and most other bacterial tick-borne infections — early treatment leads to significantly better outcomes.

Pro Tip: If you’re an Illinois hunter spending time in the field during dove season or other fall seasons, be aware that your time in the field puts you in prime tick habitat. Check out our guide to dove hunting season in Illinois for timing details that overlap with the fall tick activity window.

Staying Safe All Season Long

Tick season in Illinois is a reality of outdoor life in the Midwest, but it doesn’t have to stop you from enjoying everything this state has to offer. With the right knowledge — knowing when ticks are active, which species are in your area, and how to protect yourself — you can spend time outdoors with confidence.

A few simple habits go a long way: wear protective clothing, apply repellent, stay on trails, check yourself and your family after every outing, and act quickly if you find a tick attached. Although it’s important to remain tick-aware, ticks don’t have to keep you from heading outdoors. By taking preventive measures and watching for early signs and symptoms, residents and visitors alike can enjoy the state’s natural beauty while minimizing the chances of coming in contact with ticks any time of the year.

If you enjoy outdoor activities in neighboring states, it’s worth knowing that tick risks vary across the Midwest. Our guides on goose hunting season in Wisconsin and goose hunting season in Indiana can help you plan trips with tick awareness in mind. And if you’re in neighboring states like Michigan or Ohio, similar tick precautions apply throughout the season.