Data: lone star tick (Amblyomma americanum) and all-hard-tick (Ixodidae) occurrence records from GBIF, which includes research-grade iNaturalist citizen-science observations, 2015 to 2026. CDC county establishment data used for validation.

Tools: Python (pandas, pygbif, Uber H3 for the hex grid), matplotlib and contextily for the animation over a CARTO basemap. Interactive version built with deck.gl.

Why "adjusted": raw sighting counts mostly track where people look, not where ticks are, because citizen-science reporting has exploded. So instead of counting, each hexagon shows the share of local tick sightings that were lone star (lone star divided by all hard ticks), which cancels out observer effort. The red line is the northern edge of the range, taken as the 95th-percentile latitude of cells with real lone star signal so a single stray tick cannot distort it. It moves about 66 km north over the decade.

Live interactive map and full method: https://github.com/ahedy7/lone-star-tick-spread/tree/master





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CommercialLime9

8 comments

  1. Why? What’s interesting about this tick as someone not from Texas.

    Your corrected north edge sometimes dips below the baseline so it cannot have a +XX north of 2015 baseline. I presume this is the max distance calculated from baseline.

    This seems like a bad metric to present, why not just integrate and find the sq mileage this line has advanced? I’d propagate and include your error.

    What are the blue circles?

  2. I literally hope the anti-climate change chuds all get alpha gal syndrome.

  3. Take NYC for example:

    A ~400% increase in tick-born diseases since 2021. And rising.

    The state of New York passed a law in 2023 to make alpha-gal reportable in response to the rapid rise in incidence. The first reporting year was 2025 and there were ~140 cases. That’s compared to an estimated ~.1 cases per year in 2021 and prior.

    As opposed to encountering ticks in the wilderness, many tens of thousands more people are being exposed to diseased ticks now in concentrated, urban areas like Central Park, etc. The first Lone Star tick was officially identified in Queens/Brooklyn just last year. Previously, they had only been seen in Staten Island. It’s speculated that they are in Manhattan and the Bronx as well, but that data is being collected for release later this year.

    While you can sometimes prevent Lyme disease by taking a prophylactic dose of doxycycline within 72 hours of getting bit, alpha-gal has no such interventions.

    So expect both to become much more prevalent in urbanized areas along the east coast over the next decade.

  4. Very cool! Curious about the Asian long-horned tick next 🍻

  5. Keep those ticks south of the border thank you kindly

  6. Yeah I haven’t seen any myself but know people near the northern edge who have reported seeing them in past couple of years 🙁

  8. Looks just a depressing as the cane toad movement across Australia.

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