Size and markings separate them. An adult deer tick (blacklegged tick) is small, under 1/8 inch unfed, with dark legs and a solid dark shield behind the head; the female’s body behind that shield is reddish-orange. An adult American dog tick is about twice that size, around 1/4 inch unfed, and reddish-brown with creamy white or gray markings on its back. Deer tick nymphs, the stage most likely to bite people unnoticed, are only about the size of a poppy seed.
The difference matters because deer ticks spread Lyme disease and dog ticks don’t. But with any tick, the first job is to remove it correctly, so start there if one is attached.
If a tick is attached right now #
The CDC’s steps are the same for every species:
- Grasp the tick as close to the skin as possible with clean, fine-tipped tweezers.
- Pull upward with steady, even pressure. Don’t twist or jerk.
- Clean the bite and your hands with soap and water, rubbing alcohol or hand sanitizer.
- Keep the tick in a sealed bag or container, or taped to a card, with the date. It helps if you get sick later.
Don’t use petroleum jelly, nail polish, heat or other methods to make it let go. If you develop a rash or fever within several weeks, see your doctor and mention the bite, when it happened and where you likely picked up the tick.
Deer tick vs dog tick at a glance #
| Deer tick (blacklegged tick) | American dog tick | |
|---|---|---|
| Scientific name | Ixodes scapularis | Dermacentor variabilis |
| Adult female size (unfed) | Under 1/8 inch | About 1/4 inch |
| Adult female color | Reddish-orange body, dark brown to black shield | Reddish-brown body, creamy white shield |
| Adult male | Dark brown all over, no red | Reddish-brown with cream or gray markings covering the back |
| Legs | Dark brown to black | Reddish-brown |
| Nymph | About the size of a poppy seed | Larger than a deer tick nymph |
| Engorged female | Up to about 1/2 inch, tan, gray or dark brown | Up to 1/2 inch or longer |
| Range | Eastern US (a related western species lives along the Pacific coast) | Widely distributed east of the Rocky Mountains |
| Habitat | Woods, leaf litter, brushy edges | Grassy fields, lawns, trail edges, woods |
| Peak season | Adults spring and fall; nymphs early summer | Spring through summer |
Sources: the University of Maine’s tick lab descriptions of the deer tick and American dog tick, and the CDC’s page on where ticks live.
How to recognize a deer tick #
The University of Maine describes the adult female deer tick as brown to reddish-orange with a dark brown to black shield (scutum) and typically less than 1/8 inch long. Males are dark brown with no reddish color and have dark legs, which gives the species its “blacklegged” name.
The nymphs are the ones to watch. The CDC says nymphs pose a particularly high risk because they’re abundant and small, about the size of a poppy seed, which makes them hard to see. They’re most active in late spring and early summer. Larvae are even smaller, under 1 mm, and have six legs instead of eight.
Adults are active in spring and again in fall, and in mild weather they can be out on winter days above freezing. That’s why tick checks aren’t just a summer habit in the Northeast and upper Midwest.
How to recognize an American dog tick #
The American dog tick is noticeably larger and more ornamented. Maine’s tick lab describes the adult female as about 1/4 inch unfed, reddish-brown with a creamy-white shield, and the male as similar in color with cream or gray markings covering its entire back. They’re most active from April to August, peaking in May and June, and largely gone by October.
Dog ticks tolerate drier habitats than deer ticks, so you’ll find them in open fields, lawns and along trails, as well as in woods. Despite the name, they bite people as well as dogs.
What each tick can spread #
The CDC’s where ticks live page lists these diseases by species:
- Blacklegged (deer) tick: Lyme disease, anaplasmosis, babesiosis, ehrlichiosis, hard tick relapsing fever and Powassan virus disease
- American dog tick: Rocky Mountain spotted fever and tularemia
- Lone star tick: ehrlichiosis, tularemia, Heartland and Bourbon virus diseases, STARI and alpha-gal syndrome
The University of Maine notes that while American dog ticks can pick up Lyme disease bacteria, they appear unable to transmit it to people. So if the tick that bit you was clearly a dog tick, Lyme disease isn’t the main concern, but Rocky Mountain spotted fever and tularemia still are. Watch for fever, rash, headache or muscle aches in the following weeks, and tell your doctor about the bite.
Other ticks you might find #
- Lone star tick: The adult female has a single white dot in the middle of her back, the “lone star.” Common in the South, Midwest and Northeast. Linked to alpha-gal syndrome, a red meat allergy.
- Brown dog tick: Found worldwide and able to live its whole life indoors in kennels and homes with dogs. The CDC notes it can spread Rocky Mountain spotted fever in the southwestern US.
- Western blacklegged tick: The Pacific coast relative of the deer tick, found especially in northern California.
How to prevent tick bites #
- Use an EPA-registered repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone.
- Treat boots, clothing and gear with 0.5% permethrin, which lasts through several washings.
- Walk in the center of trails and avoid high grass and leaf litter.
- After coming inside, check your body, especially under the arms, in and around the ears, inside the belly button, behind the knees, along the hairline, between the legs and around the waist.
- Shower within two hours of coming indoors.
- Tumble dry clothes on high heat for about 10 minutes to kill ticks on dry clothing.
Check pets too, and talk to your veterinarian about tick prevention for dogs and cats.
Identifying a tick from a photo #
Put the tick in a clear bag or on white tape and photograph it from above, close up, in good light. The shield color and markings are what matter, so make sure the front half of the back is sharp. If you need help, the University of Rhode Island’s TickEncounter program runs TickSpotters, where you can submit a photo to tick experts.
Insect Identity can give you a quick first answer on the spot, offline: its 224 species include the deer tick, American dog tick and lone star tick, and it shows its best match with a confidence score and four runners-up. It doesn’t include the brown dog tick, western blacklegged tick or Gulf Coast tick, and an engorged tick looks very different from an unfed one, so a low score is a reason to ask an expert. And no app can tell you if you need medical care: that depends on symptoms, so follow the CDC guidance above and talk to your doctor. For other tick mix-ups, see spider or tick, and for bites you find in the morning, what bugs bite at night.
Frequently asked questions #
How can you tell a deer tick from a dog tick? #
Look at the size and the shield behind the head. Deer ticks are smaller, with dark legs and a solid dark shield. Dog ticks are larger and have creamy white or gray markings on the shield or across the back.
Do dog ticks carry Lyme disease? #
American dog ticks aren’t considered a Lyme disease risk; they appear unable to transmit the bacteria to people. They can spread Rocky Mountain spotted fever and tularemia, so watch for symptoms after any tick bite.
How long does a tick need to be attached to spread Lyme disease? #
According to the CDC, a tick generally must be attached for more than 24 hours before the Lyme disease bacterium can be transmitted. That’s why daily tick checks and prompt removal make such a difference.
Should I get a tick tested? #
Some labs test ticks for disease-causing germs, but a result only tells you about the tick, not about you. A tick can carry bacteria without passing them on, and a negative result doesn’t rule out infection from another bite. Your symptoms and your doctor’s advice matter more, so watch for a rash or fever in the weeks after a bite.