Asian Longhorned Ticks

Last Modified: September 11, 2024
closeup image of reddish-brown tick on stem of a plant

Adult female Asian longhorned tick on a plant stem (James Gathany, CDC)

Asian longhorned ticks (Haemaphysalis longicornis) are invasive pests that pose a serious threat to livestock in the United States. They can form large infestations on one animal and spread diseases that impact both animals and people.

In November 2017, public health officials in Hunterdon County, NJ, reported the first detection of the Asian longhorned tick outside of a U.S. port of entry inspection site. It then spread to numerous Eastern States. Asian longhorned ticks aren't normally found in the Western Hemisphere.

APHIS provides updates to State agencies to inform planning, surveillance, outreach, control, and overall collaboration on the Asian longhorned tick.

Asian longhorned tick populations in the United States are parthenogenetic, meaning an individual female can lay eggs without mating, essentially cloning herself to create the next generation. This is one reason the Asian longhorned tick is a successful invader of new geographic regions.

  • Unfed Asian longhorned ticks are light reddish-tan to dark reddish with brown, dark markings.
  • Adult females are grey-green with yellowish markings and the size of a pea after feeding. Male ticks are rare.
  • Other unfed stages of the tick are very small, about the size of a sesame seed, or even smaller.

For more details, view our pest alert (1004.99 KB) and story map about Asian longhorned ticks.

Report Signs of Animal Disease

Producers or owners who suspect an animal disease should contact their veterinarian to evaluate the animal or herd. Find an accredited veterinarian.

Animal health professionals (veterinarians; diagnostic laboratories; public health, zoo, or wildlife personnel; and others) report diagnosed or suspected cases of nationally listed reportable animal diseases to APHIS Area Veterinarians in Charge and to the State animal health official as applicable under State reporting regulations. 

Controlling Asian Longhorned Ticks