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Hemlock Woolly Adelgid

The eastern hemlock is an iconic element of our forests, creating habitat wherever it stands tall and keeping our drinking water crisp and clear. An invasive insect threatens our hemlock stands in New York – the Hemlock Woolly Adelgid (HWA) – but you can help by joining scientists, conservationists, and volunteers across the state in monitoring the spread of HWA.

Help our Hemlocks

Join the HWA Winter Mapping Challenge 

Feb 1 - March 15, 2024

The iMap user who surveys the most sites* for HWA during the challenge wins a prize from the NYS Hemlock Initiative. 

Double points for surveys in any of the survey gap counties along the "leading edge" of HWA's spread (see shaded in counties on the HWA map below).


Get outside and look for hemlock trees.


Check for white fuzz balls on the undersides of hemlock twigs - these are HWA egg masses.


Report your findings to iMap - submit a presence or not-detected record to document your effort.


  • The winner will be selected based on the number of sites (unique trails/locations) surveyed from Feb 1 - March 15th, based on iMapInvasives data.

  • To be counted, survey records must be collected and submitted to iMap using an iMap data collection tools (e.g. the mobile app).

  • Please include a clear photo with each report (especially presences).

  • Sites within the "survey gap counties" will count double (see map).

  • 2023 challenge winners are not eligible to win the 2024 challenge.

  • *Unique survey "sites" are defined as iMap records at least 100 meters apart


 Photo submitted by iMap observer 21340


Learn more

(Partnership for Regional Invasive Species Management)

Past HWA challenges

* Unique survey "sites" are defined as iMap records at least 100 meters apart


During the 2023 Challenge (Feb 1- March 15), volunteers and professionals across New York State worked together to conduct surveys for HWA and report thousands of records to iMapInvasives:

 500+ presence  and  1000+ not-detected

Thanks to all who participated!


The Winter HWA Mapping Challenge was launched for the first time Feb 12 - March 13, 2022. Through the combined efforts of professionals and volunteers, we received double the amount of reports compared to 2021 during the same period.

In particular, volunteers conducted extensive mapping in early detection regions (SLELO and the Northern Adirondacks), and along the leading edge in the Lake George region, Central NY, and Western NY.

Honorable mention went to several volunteers who reported across multiple counties and/or led group mapping efforts in their local communities.

Thanks to all who participated!

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