Tick-infested areas in Ontario are concentrated in the province’s southern and eastern regions, particularly along the north shores of Lake Erie and Lake Ontario, with established blacklegged tick populations in areas like Point Pelee National Park, Prince Edward Point, and parts of the Thousand Islands. However, ticks are expanding their range northward, and no part of southern Ontario is completely risk-free.
Why Ticks Are Expanding in Ontario
Blacklegged ticks (Ixodes scapularis) are the primary concern in Ontario because they transmit Lyme disease. Historically, these ticks were limited to isolated pockets, but climate change and ecological shifts have allowed them to spread. Warmer winters and longer springs mean ticks have more time to complete their two-year life cycle, and white-tailed deer, which serve as hosts for adult ticks, have increased in number and range. Migratory birds also play a role, carrying ticks to new areas, which is why isolated ticks are found even in northern communities.
The Ontario government, along with public health units, conducts active surveillance each year, dragging cloth flags through vegetation to collect ticks. This data is used to produce risk maps that categorize areas as ‘established’ (where reproducing populations are found) or ‘reported’ (where individual ticks are found but not yet established). These maps are updated annually, but they lag behind actual expansion by a year or two.
Known High-Risk Hotspots
As of recent public health data, the following regions have established or emerging tick populations:
- Point Pelee National Park and the surrounding Leamington area in Essex County – one of the longest-standing hotspots.
- Prince Edward Point and the eastern end of Lake Ontario near Picton.
- The Thousand Islands region along the St. Lawrence River, including parts of Leeds and Grenville.
- Long Point and the Norfolk County shoreline on Lake Erie.
- Rondeau Provincial Park and nearby Chatham-Kent.
- Parts of the Greater Toronto Area, including Rouge National Urban Park and the Scarborough Bluffs, where established populations have been found.
- Ottawa Valley, particularly around the city of Ottawa and along the Rideau Canal.
Beyond these, ‘reported’ ticks have been found in almost every southern Ontario county, and as far north as Sudbury and Sault Ste. Marie. The risk is not uniform: it is tied to specific habitats like deciduous forests, tall grasses, and leaf litter, rather than entire counties.
How Tick Habitats Work
Ticks are not active year-round. They are most active during two peak periods: spring (nymphs, roughly May to July) and fall (adults, September to November). Adults are also active on any mild winter day above 4°C. They do not jump or fly; they ‘quest’ by climbing to the top of grass or low vegetation and waiting with their front legs outstretched to latch onto a passing host.
Blacklegged ticks prefer moist, shaded environments with leaf litter and dense undergrowth. They are rarely found in short, mowed lawns or open sunny fields. The highest risk is at the edge of forests, along trails, and in areas where tall grass meets wooded cover. This is why hikers, campers, and people with rural properties are at greater risk than those who stick to paved urban paths.
How to Check for Ticks
After spending time outdoors in a risk area, perform a full-body tick check. Ticks crawl for up to several hours before attaching, so checking within 2 hours of returning indoors can prevent attachment. Use a mirror for hard-to-see areas, and check:
- Under the arms, in the armpits
- In and around the ears
- Behind the knees
- Between the legs and in the groin area
- Around the waistline and belly button
- On the scalp and hairline
Showering within 2 hours of coming indoors has been shown to reduce the risk of tick attachment. Put clothes in a dryer on high heat for 10 minutes to kill any ticks that may be on them. Do not rely on a visual check alone – ticks in the nymph stage are the size of a poppy seed and easily missed.
Removing a Tick Safely
If you find an attached tick, remove it as soon as possible. Use fine-tipped tweezers, grasp the tick as close to the skin as possible, and pull upward with steady, even pressure. Do not twist, jerk, or squeeze the tick’s body, as this can cause it to regurgitate its stomach contents into the wound. After removal, clean the area with rubbing alcohol or soap and water.
Do not use matches, petroleum jelly, or nail polish to try to make the tick detach on its own – these methods increase the risk of disease transmission. Save the tick in a sealed bag or container if you want it tested, though routine testing is not recommended by public health. Instead, monitor the bite site for 30 days for a rash (often a ‘bull’s-eye’ but not always) and watch for flu-like symptoms.
Lyme Disease Risk and What to Watch For
Not all blacklegged ticks carry the bacteria that causes Lyme disease. Infection rates in Ontario tick populations vary by location, from under 10% to over 30% in some hotspots. Even if a tick is infected, transmission usually takes at least 24 hours of attachment, and often 36-48 hours. This is why prompt removal is so effective at preventing disease.
Early symptoms of Lyme disease include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. The rash appears in about 70-80% of infected people, but it can be solid red or have a central clearing. If you develop symptoms after a tick bite, see a doctor promptly. Early treatment with antibiotics is highly effective. Left untreated, Lyme can cause arthritis, neurological issues, and heart problems.
Prevention and Protection
Public health Ontario recommends a multi-layered approach to tick prevention:
- Wear light-coloured long pants and long-sleeved shirts to spot ticks more easily.
- Tuck pants into socks – this is the single most effective clothing measure.
- Use an insect repellent containing DEET (20-30%) or icaridin (20%) on exposed skin, and permethrin-treated clothing for high-risk activities.
- Stay on cleared trails and avoid brushing against tall grass and leaf litter.
- Treat pets with vet-approved tick prevention; dogs can bring ticks into the home.
- Create a tick-safe yard by keeping grass short, removing leaf litter, and placing a 3-foot barrier of wood chips or gravel between lawn and wooded areas.
Permethrin-treated clothing is particularly effective because it kills ticks on contact, and it remains effective through multiple washes. It is not for use on skin.
Frequently Asked Questions
Are ticks in Ontario only in the south?
No. While the highest risk is in southern and eastern Ontario, blacklegged ticks have been reported in areas as far north as Thunder Bay and near the Manitoba border. The risk is lower and more patchy in the north, but it is not zero. Climate models suggest continued northward expansion.
What is the best tick repellent?
Health Canada recommends DEET and icaridin as the two most effective repellents for ticks. DEET 30% provides several hours of protection, while icaridin 20% is comparable and less likely to irritate skin. Permethrin is not a repellent but an insecticide that kills ticks on contact, and is used on clothing, not skin.
Can ticks survive the winter in Ontario?
Yes. Blacklegged ticks overwinter in leaf litter and snow cover, which insulates them from the coldest temperatures. Adults can become active on any day above 4°C, even in January. This is why tick checks are recommended year-round after outdoor activity in risk areas.
Should I get tested after a tick bite?
Routine testing of ticks or people is not recommended by Ontario public health. Instead, the recommendation is to remove the tick promptly and watch for symptoms for 30 days. If symptoms develop, see a doctor and mention the tick bite. Prophylactic antibiotics are sometimes given in high-risk situations, but they are not routine.
Are there other tick-borne diseases in Ontario?
Yes, though they are less common than Lyme. Anaplasmosis, babesiosis, and Powassan virus have been found in blacklegged ticks in Ontario. Powassan virus is rare but can be severe and can transmit within minutes of a bite, unlike Lyme. The American dog tick and lone star tick are also occasionally found in southern Ontario, but they are not established.
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