Intruder Alert: Longhorned Tick

What You Need to Know About the Invasive Tick Haemaphysalis Longicornis

Key Facts

  • Native tick in Eastern Asia1
    H. longicornis adult (left), nymph (center), and larva (right).
    H. longicornis adult (left), nymph (center), and larva (right). (Photo credit: Manigandan Lejeune, Animal Health Diagnostic Center)
  • Invasive tick in Australia and New Zealand1
  • Discovered in United States in 2017.2 Now known to inhabit the US since at least 2010.
  • First detected in New Jersey. Now found in several eastern US states and Arkansas.
  • Three life stages - each seek a host, feed, and drop off.
  • Broad host range. Prefers cattle, sheep and horses.
  • Considerable biting nuisance causing damage and irritation to livestock, humans, companion animals, and wildlife.3

Other Names

  • Cattle tick (New Zealand)
  • Bush tick (Australia)


  • Meadows and grassy areas near forests


  • Mammals and birds

Bites Humans

  • Yes

Veterinary Importance

Confirmed transmitter of bovine theileriosis and parasites that cause babesiosis infection in animals.3,4 Bovine theileriosis can reduce dairy production on cattle farms and occasionally kill calves. The ticks themselves can also cause anemia in sheep and cattle when densities are high.3

Medical Importance

In Asia, field-collected longhorned ticks can harbor pathogens that are also present, or closely related to those found in the US. These include Anaplasma phagocytophilum, Ehrlichia chaffeensis5, Babesia species, and Powassan virus6. The capacity of this tick to act as a vector for these pathogens has not been studied. This species is also considered a possible vector for Thrombocytopenia Syndrome Virus (SFTSV) in China3, an emerging infectious disease with a reported human mortality rate of up to 12.0%.7

Notable Information

Invasive populations of this species are capable of reproducing without fertilization (i.e., do not require males). This biological feature may be what allows them to spread rapidly and reach high abundance. Males are generally uncommon in invasive populations.

Potential for Spread in the U.S.

Female longhorned tick.
Female longhorned tick on a leaf. (Photo credit: James L. Occi, Rutgers University)

It is possible the longhorned tick is more widespread than currently known.

H. longicornis was first identified in the US in Hunterdon County, New Jersey, on November 9, 2017.2 The ticks successfully overwintered8, implying the potential for populations to establish regionally. This species has now been reported in numerous locations in New Jersey outside of Hunterdon County, and in other states, with reported sightings in Virginia, West Virginia, and Arkansas. After reviewing archived samples, there is evidence of species presence several years prior to the 2017 identification.

Ability of longhorned tick to feed on wildlife with large home ranges (e.g., deer) increases the potential for it to spread.

In its native range, the longhorned tick is known to feed on a wide variety of vertebrate hosts1, and invasive populations exhibit similarly broad feeding habits.9 In the US, this tick has been observed feeding on sheep, goats, horses, and cattle. It has been collected from wildlife including raccoon, opossum, and deer.

Given their cold tolerance, longhorned ticks could potentially expand northward, in addition to the risk of spread southward and westward in the US

In its native range, this species survives in relatively cold climates, generally overwintering as nymphs or adults.3 Individuals have been reported as far north as Primorsky Krai, Russia10, a region with a similar climate to the northeastern US. Furthermore, both adults and nymphs collected in China can survive at temperatures below -10 ºC - evidence that they are well-adapted for cold winters.11 The effect of cold on invasive populations in Australia and New Zealand is unclear due to relatively warm regional climates. There is a need for further evaluation regarding the thermal tolerances of the invasive population in the US. Genetic studies to determine the most likely source of this introduction may help shed light on the climatic range of the invasive US population.

For Entomologists & Public Health Professionals

We encourage public health professionals, veterinary entomologists, and other trained professionals throughout the northeastern US to begin monitoring for this invasive tick species, as well as examine historical collections of Haemaphysalis species, as the long-horned tick may have been present in the US for some time.

Haemaphysalis ticks are small, inornate ticks with eyes absent, festoons present, and with the second segment of the palpi extending laterally beyond the rectangular basis capitulum. Two species of Haemaphysalis ticks are native to the US:

  • Rabbit tick, H. leporispalustris
  • Bird tick, H. chordeilis

Both native Haemaphysalis ticks are broadly distributed across the country. A third species native to Central and South America, H. juxtakochi, is also occasionally found in the US, likely transported on migratory birds.12,13

Close up of female longhorned tick
Closeup of H. longicornis adult female mouth parts. (Photo credit: Andrea Egizi, Monmouth County Tick-borne Disease Laboratory)

Many of the characters used to distinguish members of the genus Haemaphysalis are subjective (relative lengths and shapes), particularly for the immature stages. This makes these ticks difficult to recognize without firsthand experience or access to a reference collection. As a result, DNA barcode identification has been successfully used to identify ticks in this genus.2

For those with extensive experience identifying ticks, key features to differentiate adult female H. longicornis from native congeners can be found at

If you believe that you have collected a longhorned tick, please preserve the specimen in ethanol or rubbing alcohol (70% or greater is best).

Researchers and extension specialists may send the specimen for DNA barcoding to Dina Fonseca at the Rutgers University Center for Vector Biology (180 Jones Ave., New Brunswick, NJ 08901), or to the National Veterinary Services Laboratory (USDA-APHIS) for morphological identification using Parasite Submission form 5-38.

Members of the public are encouraged to send specimens to one of the tick identification services listed at

For More Information


  1. Hoogstraal et al. 1968. Review of Haemaphysalis (Kaiseriana) longicornis Neumann (resurrected) of Australia, New Zealand, New Caledonia, Fiji, Japan, Korea, and northeastern China and USSR, and its parthenogenetic and bisexual populations (Ixodoidea, Ixodidae). J Parasitol. 54(6): 1197-1213
  2. Rainey et al. 2018. Discovery of Haemaphysalis longicornis (Ixodida: Ixodidae) parasitizing a sheep in New Jersey, United States. J Med Entomol. 55(3): 757-759
  3. Heath. 2016. Biology, ecology and distribution of the tick, Haemaphysalis longicornis Neumann (Acari: Ixodidae) in New Zealand. N Z Vet J. 64(1): 10-20
  4. Guan et al. 2010. Babesia sp. BQ1 (Lintan): molecular evidence of experimental transmission to sheep by Haemaphysalis qinghaiensis and Haemaphysalis longicornis. Parasitol Int. 59(2): 265-267
  5. Kim et al. 2003. Identification of Ehrlichia chaffeensis, Anaplasma phagocytophilum, and A. bovis in Haemaphysalis longicornis and Ixodes persulcatus ticks from Korea. Vector Borne Zoonotic Dis. 3(1): 17-26
  6. Hoogstraal. 1981. Changing patterns of tickborne diseases in modern society. Annu Rev Entomol. 26(1): 75-99
  7. Luo et al. 2015. Haemaphysalis longicornis ticks as reservoir and vector of severe fever with thrombocytopenia syndrome virus in China. Emerg Infect Dis. 21(10): 1770-1776
  8. NJDA 2018. New Jersey Department of Agriculture. Trenton, NJ
  9. Tenquist & Charleston. 2001. A revision of the annotated checklist of ectoparasites of terrestrial mammals in New Zealand. J Roy Soc New Zeal. 31(3): 481-542
  10. Heath. 2013. Implications for New Zealand of potentially invasive ticks sympatric with Haemaphysalis longicornis Neumann, 1901 (Acari: Ixodidae). Syst Appl Acarol. 18(1): 1-26
  11. Yu et al. 2014. Cold hardiness and biochemical response to low temperature of the unfed bush tick Haemaphysalis longicornis (Acari: Ixodidae). Parasit Vectors. 7(1): 346
  12. Keirans & Restifo. 1993. Haemaphysalis juxtakochi Cooley (Acari: Ixodidae), a neotropical tick species, found in Ohio. J Med Entomol. 30(6): 1074-1075
  13. Mukherjee et al. 2014. Importation of exotic ticks and tick-borne spotted fever group rickettsiae into the United States by migrating songbirds. Ticks Tick Borne Dis. 5(2): 127-134.

Prepared by James Burtis, Andrea Egizi, James Occi, Emily Mader, Manigandan Lejeune, Kirby Stafford, and Laura Harrington

The Northeast Regional Center for Excellence in Vector-Borne Diseases is supported through Cooperative Agreement Number 1U01CK000509-01 between the Centers for Disease Control and Prevention (CDC) and Cornell University. Contents are the sole responsibility of the NEVBD, and do not necessarily represent the official views of the CDC or the Department of Health and Human Services.