Asian Longhorned Tick (ALHT)
Haemaphysalis longicornis Neumann
The Asian Longhorned Tick (ALHT) is an invasive species native to China, Japan, and Korea, and has also been introduced to New Zealand, Australia, and several Pacific islands. This tick can transmit multiple bacterial, viral, and protozoan pathogens, including Theileria orientalis Ikeda, a protozoan debilitating cattle disease associated with anemia and abortion.
Heavy infestations can cause severe blood loss, weakness, and death. In New Zealand and Australia, ALHT infestations have been linked to reductions in dairy production of up to 25% (Hoogstral et al. 1968; Heath 2016).
ALHT was first detected in the United States in New Jersey in 2017 and has since spread to more than 20 states. The most recent confirmed detections were in Iowa and Michigan in 2025 (Figure 1). While ALHT has not yet been reported in Nebraska, livestock producers should be aware that it is present in nearby states and could eventually be found here.
A unique concern with ALHT is its reproductive capacity. Females can reproduce either sexually or asexually, but only the asexual form has been identified in the U.S. In this form, all offspring are female, allowing populations to reach extremely high densities in just a few months.
A single female can lay 900–3,000 eggs in one event before dying. Development from egg to adult averages 89 days, with feeding stages active for about 57 days (Hoogstral et al. 1968).
ALHT is a three-host tick, meaning each life stage—larva, nymph, and adult feeds on a separate host before dropping off to molt to the next stage. However, if hosts are limited, all life stages may feed on the same animal, such as pastured cattle (Rainey et al. 2018). Feeding to full engorgement typically takes 3–6 days.
In the U.S., ALHT has been found in warm, humid habitats such as tall grassy areas near forests and meadows. The ticks are light brown and very small, about the size of a sesame seed or smaller (Figure 2) and can be mistaken for other species.
They have been collected from numerous domestic animals (sheep, goats, dogs, cats, horses, cattle, chickens), wildlife, and people.
Monitoring and Identification
Livestock producers should routinely check animals, especially around the eyes, ears, limbs, tail, and udder.
Cattle should be inspected during handling events such as vaccinations, ear tagging, pregnancy checks, or artificial insemination. Collected ticks should be placed in alcohol and taken to a veterinarian or extension office for identification.
Young animals (under six months) and pregnant cows are particularly vulnerable. Cow-calf producers should be especially cautious when introducing naïve animals into pastures where ALHT is present.
Once infected with Theileria, cattle remain carriers for life and may relapse during stressful periods. There is currently no direct treatment for Theileria infection.
Management and Control
ALHT is highly susceptible to synthetic pyrethroid insecticides. The best control is achieved with whole-animal sprays or pour-ons, or oilers/backrubbers. Additional management practices include:
- Maintaining short grass along tree lines.
- Fencing livestock away from wooded areas.
- Implementing pasture rotation to break the tick life cycle.
Literature Cited
Heath, A.C.G., 2016. Biology, ecology and distribution of the tick, Haemaphysalis longicornis Neumann (Acari: Ixodidae) in New Zealand. New Zealand veterinary journal, 64(1), pp.10-20.
Hoogstraal, H., Roberts, F.H., Kohls, G.M. and Tipton, V.J., 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). The Journal of parasitology, pp.1197-1213.
Raney, W.R., Perry, J.B. and Hermance, M.E., 2022. Transovarial Transmission of Heartland Virus by Invasive Asian Longhorned Ticks under Laboratory Conditions. Emerging infectious diseases, 28(3), p.726.
