This article was featured in the 2024 Winter Newsletter by, Mitch O’Neil-New Yor Natural Heritage Program/iMapInvasives.

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 called hemlock woolly adelgid (HWA) threatens our hemlock stands in New York, but you can help by joining scientists, conservationists, and volunteers across the state in monitoring the spread of HWA.

From Feb 1st – March 15th, the NY Natural Heritage Program is hosting the 3rd Annual HWA Winter Mapping Challenge in partnership with the NYS Hemlock Initiative. Join the challenge to help map HWA along the “leading edge” of its current range, and compete to win the prize.

To participate: find some hemlock trees in your area, check for HWA egg masses (look for white fuzz balls on the undersides of twigs), and report your findings to NY iMapInvasives – whether you find it or not. Not-detected records can be just as valuable as presence records.

The iMap users who survey the most sites for HWA will win the challenge and your very own Hemlock Initiative hat!

Oneida, Jefferson, and Lewis counties will count double in your totals since these counties are near the leading edge of HWA’s currently known distribution.

Visit to learn more about the challenge and connect with HWA mapping efforts in your area. You can also view the recording of our January 31st kick-off webinar, where Caroline Marschner from the Hemlock Initiative delivered a crash course on the importance of hemlocks and HWA, and how to survey for them.

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