The Asian Longhorned Tick (ALT), Haemaphysalis longicornis, is an invasive tick species first identified in the United States in 2017. Since then, it has spread rapidly across much of the eastern U.S. and continues to expand its range. While not new to other parts of the world, ALT presents unique challenges for U.S. cattle producers due to its ability to reproduce quickly and reach extremely high population levels.
Why ALT Is Different
Unlike most tick species, ALT can reproduce without males. A single female can lay up to 3,000 eggs, allowing populations to explode under favorable conditions. ALT thrives in low-lying, swampy areas, wooded edges, and tall grass, and producers often report heavy infestations after cattle graze these environments.
ALT has been found on a wide range of hosts, including cattle, sheep, goats, horses, wildlife, pets, and birds, making complete control difficult.
ALT on Cattle
Infestations on cattle can be dramatic, with large numbers of ticks found in the ears, groin, and reproductive areas. Not all cattle are affected equally, and tick burden often reflects the level of infestation in the pasture.
Most cattle infested with ALT do not show obvious clinical disease. Some animals may appear unthrifty or show reduced body condition or weight gain, though these signs are often influenced by additional factors such as nutrition or other parasites. In rare cases, extremely heavy infestations may contribute to anemia.
If cattle appear noticeably ill, ALT is unlikely to be the only issue present, and producers should work with their veterinarian to evaluate the herd.
Identification and Control
Proper identification of tick species is important. Ticks can be collected and preserved in alcohol and submitted through Cooperative Extension services, state departments of agriculture, or land-grant universities for identification.
ALT appears susceptible to many common cattle parasiticides, including:
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Macrocyclic lactones (such as Dectomax®, Eprinex®, Cydectin®, Ivomec®)
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Organophosphates
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Pyrethroid-based products
Fly tags labeled for tick control may also be effective. Pour-on products may have limitations in reaching areas where ticks cluster, such as ears and groin regions. Reinfestation is common if cattle remain on heavily infested pastures after treatment levels decline.
Pasture treatments are generally not recommended, though targeted treatment of high-density areas may be considered with expert guidance. Management practices such as clipping pastures and limiting access to wooded or swampy areas may help reduce exposure but are not always practical.
Key Takeaways for Wagyu Producers
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Asian Longhorned Tick populations can build rapidly in certain environments
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Most infested cattle do not develop clinical disease
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Heavy infestations may affect performance in some animals
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Tick control requires an integrated approach, not a single treatment
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Work closely with your veterinarian to develop a herd-specific plan
As Asian Longhorned Tick continues to spread, awareness and proactive management are the best tools Wagyu producers have to protect herd health and performance.