Deer Tick: What It Looks Like, Bites & Lyme

The blacklegged tick, often called the deer tick, is the small tick with black legs that spreads the bacteria behind Lyme disease. Its nymphs, about the size of a poppy seed, cause most infections because they’re so easy to miss. The one thing to do: check yourself, children and pets after time outdoors, and remove any tick promptly with fine-tipped tweezers.

This page covers how to identify a blacklegged tick at each stage, where it lives and the signs to watch for after a bite. It rests on CDC and University of Kentucky guidance; see a doctor about any symptoms after a tick bite.

How to Identify a Blacklegged Tick: Black Shield, Black Legs

Adult female: about 1/8 inch, with a reddish-orange body, a black shield behind the head and black legs.
Adult male: smaller and all dark brown to black.
Nymph: about the size of a poppy seed, semi-transparent with dark legs.
Engorged ticks swell and turn grayish; a fed adult female reaches about 3/8 inch.

The CDC notes that Lyme disease is most common in the Northeast, mid-Atlantic and upper Midwest. A close relative, the western blacklegged tick, lives along the Pacific Coast.

A blood-swollen female blacklegged tick, brown and bean-shaped, with short legs at the front

A blacklegged tick after feeding: swollen, brown and bean-shaped, looking very different from an unfed one. Photo: NIAID (CC BY 2.0), via Wikimedia Commons.

Blacklegged Tick Life Stages: Smaller Than You Think

Stage	Size	Legs	When active
Larva	Smaller than a poppy seed	Six	Late summer
Nymph	About the size of a poppy seed	Eight	Late spring and summer
Adult	About the size of a sesame seed	Eight	Fall through early spring, on days above freezing

Each stage feeds once, on a different host. Unlike most ticks, adults stay active through winter whenever it’s above about 40°F (University of Kentucky), so a warm winter walk can still bring one home.

Deer Tick vs. Other Ticks: Small and Plain

Tick	Look for	Main diseases
Blacklegged (deer) tick	Small; female reddish-orange with a black shield and black legs	Lyme disease, anaplasmosis, babesiosis
Lone star tick	Female has one white spot on the back	Ehrlichiosis, alpha-gal syndrome
American dog tick	Larger, brown with white or silvery markings	Rocky Mountain spotted fever

Only ticks in this genus (Ixodes) can transmit the Lyme bacteria; a lone star tick bite carries no Lyme risk (University of Kentucky). A tiny, flat, reddish-brown bug in a mattress seam is more likely a bed bug.

Where You’ll Find Them: Leaf Litter and Woodland Edges

Leaf litter and shaded, humid woodland edges
Tall grass and brush along trails
Yards next to woods, stone walls and woodpiles
On pets and on people after outdoor activities

White-footed mice are a common natural reservoir for the Lyme bacteria, which is one reason ticks near woods and stone walls matter.

How Ticks Find People: Questing, Not Jumping

Ticks don’t jump or fly. They wait at the tips of grass and low plants with their front legs outstretched, a behavior called questing, and climb onto people and pets brushing past. They often crawl for a while before biting, usually at the hairline, behind the ears, in the armpits, behind the knees and around the waist.

Are Blacklegged Ticks Dangerous? Lyme and More

Yes. Besides Lyme disease they can spread anaplasmosis, babesiosis, Powassan virus and other infections. The good news: a blacklegged tick has to feed for a long time, about 36 hours, before it passes on the Lyme bacteria (University of Kentucky), so finding and removing ticks the same day matters.

The CDC lists fever, headache, fatigue and an expanding red rash called erythema migrans as typical symptoms of Lyme disease. The rash can look like a bull’s-eye, but often doesn’t. See a doctor if any of these appear in the weeks after a tick bite, and mention the bite. Untreated, Lyme disease can spread to the heart, nervous system and joints. Other bite marks are compared in bug bite pictures.

How to Confirm It’s a Blacklegged Tick

Look at the legs and shield: both black on an adult female.
Check the size: a sesame seed for adults, a poppy seed for nymphs.
Keep the tick in a sealed bag, on tape or in a small jar with rubbing alcohol, and note the date. If symptoms appear, it helps a doctor know what kind of tick it was.

What to Do: Remove It, Then Prevent the Next One

Use fine-tipped tweezers to grip the tick as close to the skin as possible and pull upward with steady, even pressure. Clean the area afterward. Don’t twist, burn or smother the tick.

Wear repellent and long pants on trails, check yourself, children and pets daily after being outdoors, and shower soon after. In the yard, keep grass short and leaf litter cleared, and put a strip of wood chips or gravel between lawns and woods; how to get rid of ticks walks through the whole yard plan. For other pests, browse all pest guides.

Blacklegged tick