Asian Longhorned Tick

Scientific Name: Haemaphysalis longicornis

Common Name: Asian longhorned tick

Description: Adult Asian longhorned ticks are small (roughly 1/8 inch long), reddish-brown ticks with no distinctive body patterns. Unfed adults are generally about the size of a sesame seed, while engorged adult females may grow to approximately 1/2 inch in length. Males are rare in U.S. populations because females can reproduce without mating.

Habitat/Range: The Asian longhorned tick is native to eastern Asia but has become established in Australia, New Zealand, and parts of the western Pacific. In the United States, it was first confirmed in New Jersey in 2017 and has since been detected in numerous eastern states. It is commonly found in grassy or brushy habitats, pastures, transition areas between forests and grasslands, and areas used by livestock or wildlife. In Maine, a single Asian longhorned tick was confirmed in 2025. Follow-up surveillance did not detect additional specimens, and it is not currently known to be established in the state.

Life Cycle/Hosts: The Asian longhorned tick is a three-host tick, meaning it typically feeds on a different host during each active life stage: larva, nymph, and adult. It feeds on a wide range of animals, including domestic cattle, sheep, horses, dogs, as well as wildlife, such as squirrels, rabbits, woodchucks, raccoons, deer, birds, and occasionally humans. Unlike most ticks, female Asian longhorned ticks in the United States can reproduce without mating. This allows a single female to establish a new population and can result in very large infestations on animals or in the environment.

Medical/Veterinary Importance: The Asian longhorned tick is primarily a veterinary and livestock concern in the United States. Heavy infestations can cause blood loss, reduced weight gain, decreased milk production, and, in severe cases, death in livestock. In the United States, it is capable of transmitting Theileria orientalis Ikeda, a pathogen that can cause serious disease in cattle. In other parts of the world, Asian longhorned ticks are associated with several human and animal pathogens. However, their role in transmitting human disease agents in the United States remains uncertain.