10/13/2026
CALLING ALL FOREST EXPLORERS: Help Us Find the Lingering Hemlocks in Rothrock! đ˛
Pennsylvaniaâs state tree is in trouble. Eastern hemlock is being devastated by two invasive insects, the hemlock woolly adelgid and the elongate hemlock scale. Hemlocks anchor our cool, shaded streamside forests, protect water quality, and shelter wildlife from brook trout to songbirds. Losing them changes the whole forest.
But thereâs hope, and you can help us find it.
What is the Lingering Hemlock Project?
In places where 80% or more of the hemlocks have died, researchers look for the rare trees still standing alive and healthy among the dead. These âlingering hemlocksâ may carry natural genetic resistance to these pests. If we can find them, scientists can study them and work to protect and propagate that resistance, giving hemlocks a fighting chance to return to Pennsylvaniaâs forests.
Why it matters to the Bureau of Forestry
The DCNR Bureau of Forestry is charged with conserving and sustaining the long-term health, diversity, and productivity of Pennsylvaniaâs forests. Safeguarding hemlock for future generations is exactly that mission in action.
How the Lingering Hemlock Project Works
In areas where hemlock mortality hasnât yet reached 80%, LHP will install Hemlock Health Monitoring Plots. Each plot covers about 20â40 living hemlocks. They mark and record the plot location, tag the trees, and document the site and any dead hemlocks. Then they revisit each year to track tree health, pest presence, and crown condition. Following hemlock decline over time helps researchers catch that 80% mark right as it happens, so we can find and save any resistant trees before theyâre lost.
How YOU can help: use TreeSnap!
If you spot a hemlock that looks healthy among dying or dead hemlocks, report it:
1ď¸âŁ Download the free TreeSnap app from your smartphoneâs app store
2ď¸âŁ Open the app
3ď¸âŁ Under âObserve,â select âHemlockâ
4ď¸âŁ Complete the prompts. Under âCollection purpose,â select âLingering hemlock(s) data reportingâ
5ď¸âŁ Keep answering as new questions appear. Many are optional, but the more information you give, the better it is for the researcher reviewing your submission
6ď¸âŁ Select âSaveâ
7ď¸âŁ Choose âUpload Nowâ or âUpload Later.â Choose âUpload Laterâ if youâre outside cellular service. TreeSnap will remind you when an observation is ready to upload
đĽ Not sure what to look for? Watch the training video and find helpful field guides, photo tips, and more here:
đ https://lingeringhemlockproject.org/lingeringhemlocksearch/lingering-hemlock-search-resources/
Every hiker, angler, hunter, birder, and curious walker in the woods is a potential citizen scientist. Your sharp eyes could help save a species! So next time youâre out on the trails, keep watch. Letâs find those lingering hemlocks in Rothrock! đđ˛