Blacklegged Tick (Deer Tick)
Ixodes scapularis
The blacklegged tick (Ixodes scapularis), commonly called the deer tick, is a small, hard-bodied tick widely distributed across the eastern United States. It is medically important because it can transmit several pathogens that cause human illness, including Lyme disease, anaplasmosis, babesiosis, hard tick relapsing fever, ehrlichiosis, and Powassan virus disease.
Nymphs and adult females are the stages most often reported biting people, although larvae can also bite humans.
Common in forests & grassy areas
Active in spring through fall
Can transmit serious diseases
Identification & Key Features
Identification & Key Features Blacklegged ticks are relatively small and can be difficult to notice, particularly during the nymph stage. Like other hard ticks, they have a hardened plate on the upper surface called a scutum, or shield. Their appearance varies depending on sex, life stage, and whether they have fed.
Adult Female
An unfed adult female typically has:
- Dark brown to black legs
- A reddish-brown to reddish-orange body
- A dark brown to black scutum directly behind the mouthparts
- Relatively long, straight mouthparts
- An oval, flattened body when unfed
- Eight legs
In adult females, the scutum covers the front portion of the dorsal surface. Because the scutum does not expand, the softer portion of the body enlarges considerably during feeding.
After feeding, an adult female can become much larger and may appear tan, gray, or dark brown, making an engorged tick look quite different from an unfed one.
Adult Male
Adult males are generally:
- Slightly smaller than adult females
- Predominantly dark brown to black
- Equipped with eight dark legs
- Without the reddish coloration typically seen in unfed adult females
In adult males, the scutum covers the entire dorsal surface of the body, giving the male a darker, more uniform appearance.
Nymph
Blacklegged tick nymphs:
- Have eight legs
- Are approximately the size of a poppy seed
- Are very small and difficult to see
- May be easily overlooked when attached to the skin
Their small size is one reason nymphs are particularly important in human tick exposure.
Larva
Blacklegged tick larvae:
- Have six legs
- Are typically less than 1 mm in size
- Are the smallest active life stage
- Develop into eight-legged nymphs after feeding and molting
Additional Identification Features
Blacklegged ticks also have several characteristics that can help distinguish them from other species:
- Dark legs
- Relatively long, straight mouthparts
- No ornate white markings
- No festoons, the small divisions or grooves found along the rear edge of many other hard ticks
- No eyes – unlike several other common hard tick species, blacklegged ticks lack visible lateral eyes.
Identification Tip
Look for:
✓ Dark legs
✓ Reddish-brown or reddish-orange body in adult females
✓ Dark scutum
✓ No ornate white markings
✓ Long, straight mouthparts
✓ No festoons
✓ No eyes
✓ Very small nymphs
Geographic Distribution & Habitat
Geographic Distribution & Habitat Geographic Distribution
The blacklegged tick is widely distributed across the eastern United States, including large portions of the:
- Northeast
- Mid-Atlantic
- Upper Midwest
- Southeast
The presence and abundance of blacklegged ticks vary by location. The percentage of ticks carrying particular pathogens also differs significantly from one region to another.
The presence of blacklegged ticks in an area does not mean the risk of every blacklegged tick-borne disease is the same throughout their range.
Preferred Habitat
Blacklegged ticks are commonly encountered in:
- Wooded areas and forests
- Leaf litter
- Brush and low vegetation
- Woodland edges
- Grassy or brushy areas bordering woods
- Forest trail edges and vegetation bordering trails
- Shaded suburban landscapes
- Areas around stone walls or woodpiles where suitable habitat and animal hosts are present
They generally favor shaded, humid environments that help protect them from drying out.
Hosts
Blacklegged ticks can feed on a wide variety of:
- Mammals
- Birds
- Reptiles
- Amphibians
Immature ticks commonly feed on smaller animals such as mice, other small mammals, and birds, while adult females often feed on larger mammals such as white-tailed deer.
White-tailed deer are important hosts for adult blacklegged ticks and help support tick populations. However, deer are not reservoirs for the bacteria that cause Lyme disease and do not infect feeding ticks with these bacteria.
Distribution Map
Life Cycle & Seasonal Activity
Life Cycle & Seasonal Activity The blacklegged tick generally completes its life cycle in about two years, although development can vary with environmental conditions.
Its four life stages are:
Egg → Larva → Nymph → Adult
After hatching, larvae and nymphs require a blood meal before molting to the next stage. Adult females require a blood meal to produce eggs, while adult males typically do not take a substantial blood meal.
Blacklegged ticks commonly use different hosts during their active life stages.
Egg
Adult females generally lay eggs during the spring, often in protected environments such as leaf litter.
A female may lay several thousand eggs before dying.
Larva
Eggs hatch into tiny six-legged larvae during the summer.
Larvae seek a host and commonly feed on small mammals, birds, and other animals. After feeding, they drop from the host and eventually molt into nymphs.
Nymph
Nymphs become particularly active during the following spring and summer.
They:
- Have eight legs
- Are extremely small
- Feed on another host
- Can bite humans
After feeding, nymphs drop from the host and eventually molt into adults.
Adult
Adults develop later in the year and become particularly active during the fall.
Adult females often seek larger mammals for a blood meal. After feeding and mating, females eventually lay eggs the following spring, beginning the life cycle again.
Seasonal Activity
Spring
Nymph activity increases, and adults may also be encountered.
Summer
Nymphs are highly active, while larvae become active during the summer.
Fall
Adult blacklegged ticks become particularly active.
Winter
Adults may continue searching for hosts whenever temperatures rise above freezing.
Important Seasonal Note
Blacklegged ticks are not strictly a warm-weather problem.
Adult blacklegged ticks can remain active during mild winter weather when temperatures are above freezing.
Diseases & Health Risks
Diseases & Health Risks Blacklegged ticks can transmit pathogens responsible for several human diseases.
Lyme Disease
Pathogens: Borrelia burgdorferi and Borrelia mayonii
Anaplasmosis
Pathogen: Anaplasma phagocytophilum
Babesiosis
Pathogen: Babesia microti
Babesiosis is caused by a parasite, rather than a bacterium or virus.
Hard Tick Relapsing Fever
Pathogen: Borrelia miyamotoi
Ehrlichiosis
Pathogen: Ehrlichia muris eauclairensis
The recognized geographic distribution of this particular ehrlichiosis is more limited than the overall range of the blacklegged tick.
Powassan Virus Disease
Pathogen: Powassan virus
Important Health Information
Not every blacklegged tick is infected.
The percentage of ticks carrying a particular pathogen varies by geographic location, life stage, and pathogen. Being bitten by a blacklegged tick therefore does not automatically mean an infection will occur.
Attachment Time
Remove attached ticks as soon as possible.
For Lyme disease, longer attachment generally increases transmission risk, and prompt tick removal can substantially reduce the risk of infection.
However, attachment time is not the same for every pathogen.
Remove attached ticks as soon as possible. Transmission time varies depending on the pathogen, and there is no single “safe” attachment time that applies to every tick-borne infection.
Coinfections
Blacklegged ticks may occasionally carry more than one pathogen. As a result, coinfections can occur, including combinations involving Lyme disease, anaplasmosis, and babesiosis.
Bite Prevention & Protection
Bite Prevention & Protection Before Going Outdoors
Use additional caution in:
- Wooded areas
- Brushy areas
- Tall grass
- Leaf litter
- Overgrown vegetation
- Woodland edges
Stay near the center of cleared trails whenever practical.
Use Insect Repellent
EPA-registered repellents may contain active ingredients such as:
- DEET
- Picaridin
- IR3535
- Oil of Lemon Eucalyptus (OLE)
- para-menthane-diol (PMD)
- 2-undecanone
Always follow product label directions.
Products containing OLE or PMD should not be used on children younger than 3 years.
Protect Clothing & Gear
Products containing 0.5% permethrin may be used on approved clothing and outdoor gear according to label directions.
Examples include:
- Pants
- Socks
- Boots
- Jackets
- Tents
- Outdoor equipment
Do not apply permethrin products directly to the skin.
After Spending Time Outdoors
Perform a thorough tick check, paying particular attention to:
- Under the arms
- In and around the ears
- In and around the hair
- Inside the belly button
- Around the waist
- Between the legs
- Behind the knees
Because blacklegged tick nymphs are extremely small, a mirror and magnifier can help with identification.
Also check:
- Clothing
- Pets
- Backpacks
- Outdoor gear
- Coats and shoes
Ticks can be carried indoors before attaching to a person.
Shower
Shower within two hours of coming indoors.
Showering may help wash off unattached ticks and provides another opportunity to perform a thorough tick check.
Clothing
For dry clothing:
Tumble dry on high heat for 10 minutes after coming indoors to help kill ticks.
Damp clothing may require additional drying time.
If You Find an Attached Tick
Remove it as soon as possible.
- Use clean, fine-tipped tweezers.
- Grasp the tick as close to the skin’s surface as possible.
- Pull upward and away from the skin using steady, even pressure.
- Do not twist or jerk the tick.
- Avoid crushing the tick with your fingers.
- Clean the bite area and your hands afterward.
- Check the rest of your body for additional ticks.
Do Not Use
Do not try to make an attached tick detach using:
- Petroleum jelly
- Heat
- Nail polish
- Other substances
These methods may delay proper removal.
After Removal
Monitor the bite area and how you feel during the following days and weeks.
If you develop a rash, fever, or other concerning symptoms, contact a healthcare professional and mention the recent tick bite.
Around Your Home
To help reduce tick habitat around residential properties:
- Remove leaf litter
- Clear tall grass and brush around homes and lawn edges
- Mow grass regularly
- Keep wood stacked neatly in a dry location
- Keep playground equipment, decks, and patios away from wooded edges when practical
- Create an approximately 3-foot-wide barrier of wood chips or gravel between lawns and wooded areas
- Discourage unwanted wildlife from frequently used areas
- Remove debris that may create favorable tick habitat
Identification Gallery
Identification Gallery Adult Female
Adult Female Blacklegged Tick
Reddish-brown to reddish-orange body with dark legs and a dark scutum covering the front portion of the back.
Adult Male
Adult Male Blacklegged Tick
Usually darker in appearance because the scutum covers nearly the entire back.
Nymph
Blacklegged Tick Nymph
A very small, eight-legged stage, often compared in size to a poppy seed.
Larva
Blacklegged Tick Larva
The smallest active life stage. Larvae have six legs instead of eight.
Engorged Female
Engorged Adult Female Blacklegged Tick
After feeding, the female becomes much larger and may appear tan, gray, or brown.
Quick Identification
Female: Reddish-brown body with a dark scutum near the front.
Male: Mostly dark, with the scutum covering nearly the entire back.
Nymph: Very small with eight legs.
Larva: Extremely small with six legs.
Life Stages:
Larva → Nymph → Adult
