Ticks are small, blood-feeding pests that can spread germs causing illness.

In the United States, the new Asian longhorned tick has emerged as a new and rapidly spreading threat.

First detected in 2017, it’s now a major concern for farmers, pet owners, people, and health officials.

Where Did the Asian Longhorned Tick Come From, and Why?

The Asian longhorned tick, or Haemaphysalis longicornis, is native to East Asia, thriving in countries like China, Japan, Korea, and Russia’s Far East. It has also spread to Australia, New Zealand, and Pacific islands, where it’s a known pest for livestock and wildlife.

It likely arrived in the U.S. via imported animals, plants, or travelers’ belongings through trade or travel from Asia.

Genetic studies suggest at least three female ticks from northeast Asia introduced it.

The first major sighting was in November 2017 on a sheep farm in Hunterdon County, New Jersey, though it had been intercepted at U.S. ports earlier.

It thrives here due to warm, humid climates similar to its homeland, and climate change may be expanding its range.

This tick is unique because females can reproduce without males, laying 2,000 to 3,000 eggs at a time, all clones.

This allows rapid population growth, with thousands sometimes infesting a single animal. Its life cycle—egg, larva (seed-sized), nymph (small and fast), and adult (pea-sized when fed)—takes about a year, with each stage seeking a new host.

Who and What Animals Are Affected, and Why?

The Asian longhorned tick targets a wide range of hosts, aiding its spread. It feeds on:

• Livestock: Cows, sheep, goats, horses, pigs, and chickens. Heavy infestations cause blood loss, weakening or killing animals.
• Wildlife: Deer, bears, foxes, raccoons, opossums, squirrels, groundhogs, skunks, and birds like geese, owls, and hawks.
• Pets: Dogs and cats.
• Humans: Rare, but bites have occurred, such as in New York in 2019.

Its versatility in hosts stems from its adaptability to various animals and environments. It prefers warm, humid areas with grass, woods, or brush.

Larvae and nymphs, tiny as poppy seeds, hide in tall vegetation, while adults (reddish-brown, apple seed-sized unfed) climb onto hosts.

For animals, the primary danger is severe blood loss, reducing milk or wool production and potentially killing young or weak livestock.

It also spreads Theileria orientalis Ikeda, a parasite causing anemia or death in cattle, confirmed in U.S. cases. For humans, it hasn’t yet spread diseases here, unlike in Asia, where it carries viruses causing fever or spotted fevers.

However, some U.S. ticks test positive for Lyme or anaplasmosis germs, raising concerns about future risks.

Where Is It Found in the U.S., and Why There?

The tick is concentrated in the eastern U.S., spreading via animals, birds, or human activity. As of 2025, it’s confirmed in over 20 states, primarily east of the Mississippi, including Michigan. Warm, humid environments and abundant hosts fuel its expansion.

Below is a list of key states where it’s been reported:

State	Notes
New Jersey	First major find; widespread on farms and in woods.
New York	Human bites reported; found in parks and lawns.
Pennsylvania	Common in forests and fields; some carry germs.
Virginia, West Virginia, Maryland	Early spread; affects wildlife and livestock.
North Carolina, South Carolina	Southern expansion; significant livestock impact.
Ohio	Western edge; caused cattle deaths (e.g., three cows in 2021).
Connecticut, Maine	Northern reach; growing presence.
Michigan	Confirmed in 2024; found in grassy areas and on wildlife.
Illinois, Iowa	Recent detections in 2024-2025; monitoring underway.
Arkansas, Missouri	Westernmost spread; farm concerns.
Kentucky, Tennessee	Recent finds; river valleys aid spread.
Delaware, Rhode Island	Newer reports; coastal and wooded areas.
Georgia	Emerging in southern grasslands; livestock at risk.

It thrives in grassy fields, forest edges, and suburban lawns, not just deep woods.

The USDA, CDC and other state agencies track its spread with maps to guide control efforts.

Why Is the Asian Longhorned Tick a Threat?

Its rapid reproduction and host range make it a menace.

On farms, it causes significant losses by killing livestock through blood loss or diseases like theileriosis.

A single infestation can weaken entire herds, cutting profits. For pets and wildlife, it causes stress and potential disease transmission.

For humans, the risk is currently low but worrisome. Its ability to carry local pathogens like Lyme could evolve, and its presence in open grassy areas increases bite risks.

Climate change worsens the problem by expanding habitable zones.

Control measures include daily checks on animals and skin after outdoor activities, using DEET-based repellents, wearing long clothing, and mowing tall grass.

Farmers use tick-killing sprays, and reporting sightings to local health departments helps track and contain spread.

Other Dangerous Ticks in the U.S. and Their Locations

Beyond the Asian longhorned tick, the U.S. faces several other harmful ticks spreading diseases like Lyme, fevers, and allergies.

Below is a summary of major ticks, their primary states, and risks:

Tick Type	Key States/Regions	Main Diseases	Why Dangerous
Blacklegged (Deer Tick)	Northeast (NY, PA, NJ, CT, MA, RI), Upper Midwest (WI, MN, MI), Pacific Coast (CA)	Lyme, Anaplasmosis, Babesiosis, Powassan	Leading Lyme carrier; tiny nymphs hard to detect. Over 300,000 Lyme cases yearly. Michigan has high Lyme rates in Upper Peninsula.
Lone Star Tick	Southeast (TX, FL, GA, NC, SC, VA), Midwest (MO, AR, IL, KY), Northeast edges	Ehrlichiosis, Alpha-gal (meat allergy), Heartland Virus	Aggressive; causes red meat allergy. Common in southern MI and GA forests.
American Dog Tick	East of Rockies (most states, including MI, OH, KY), some West	Rocky Mountain Spotted Fever, Tularemia	Infects dogs and humans; fever can be fatal if untreated.
Western Blacklegged Tick	West Coast (CA, OR, WA)	Lyme	Similar to deer tick but less widespread.
Rocky Mountain Wood Tick	Rockies (MT, WY, CO, ID)	Rocky Mountain Spotted Fever, Colorado Tick Fever	Can cause paralysis in rare cases.
Brown Dog Tick	Southwest (AZ, TX), nationwide on dogs (including MI, GA)	Rocky Mountain Spotted Fever	Indoor pest; infests kennels and homes.

The Northeast, including Michigan’s Upper Peninsula, leads in tick-borne diseases, with Lyme cases rising.

Southern states like Georgia face growing lone star tick issues, especially meat allergies. All states report some tick activity, but warm, wooded, or grassy areas are hotspots. Check CDC county-level maps for local risks.

Staying Safe

Ticks are a growing challenge, but awareness helps.

Remove ticks promptly with tweezers, seek medical help for fevers or rashes, and stay vigilant outdoors.

With the Asian longhorned tick spreading in states like Michigan, Georgia, and beyond, simple steps like checking skin, using repellents, and reporting sightings can keep you, your pets, and livestock safer.