Rapid invasion and expansion of the Asian longhorned tick (Haemaphysalis longicornis) into a new area on Long Island, New York, USA.

Since its discovery in the United States in 2017, the Asian longhorned tick (Haemaphysalis longicornis) has been detected in most eastern states between Rhode Island and Georgia. Long Island, east of New York City, a recognized high-risk area for tick-borne diseases, is geographically close to New Jersey and New York sites where H. longicornis was originally found. However, extensive tick surveys conducted in 2018 did not identify H. longicornis on Long Island. In stark contrast, our 2022 tick survey suggests that H. longicornis has rapidly invaded and expanded in multiple surveying sites on Long Island (12 out of 17 sites). Overall, the relative abundance of H. longicornis was similar to that of lone star ticks, Amblyomma americanum, a previously recognized tick species abundantly present on Long Island. Interestingly, our survey suggests that H. longicornis has expanded within the Appalachian forest ecological zone of Long Island's north shore compared to the Pine Barrens located on the south shore of Long Island. The rapid invasion and expansion of H. longicornis into an insular environment are different from the historical invasion and expansion of two native tick species, Ixodes scapularis (blacklegged tick or deer tick) and A. americanum, in Long Island. The implications of H. longicornis transmitting or introducing tick-borne pathogens of public health importance remain unknown.