Here’s more info about the little buggers.
What’s Happening to the Hemlocks?
The eastern hemlock is a beautiful, long-lived evergreen tree found in forests across the Eastern United States. Because they are shade tolerant, the tallest specimens are found in well-established forest environments, where they slowly grow under the faster sprouting trees such as white pines. Shade tolerant trees will grow in shade, but will grow quickly when an opening in the canopy from a tree fall or other disturbance happens.
Succession is a word used to describe changes in ecosystems over time. Hemlocks are trees that appear in mid to late succession New England forests. Around Groton, you may have noticed that there seem to be old stone walls winding through many forests. The stone walls show where pastures and farming fields were before there were forests. As farmers moved away and sold their lands, forests grew. The forests in and around Groton are often early to mid succession, showing that the forests are often around 80-100 years old.
Looking closely at the green fronds of the hemlock, you may notice tiny white cottony clumps where the needles meet the stem. These are the signs of an invasive bug called the hemlock woody adelgid or HWA. The HWA is unusual in that it’s active in winter, and pierces twigs to feed, eventually damaging and killing the host hemlock. Hemlocks are a critical species, as they often grow in rocky areas, stabilizing hillsides and riverbanks, and provide food and canopy shelter to many species including moose, amphibians, and migratory birds. Vulnerable trees may die within 3-5 years of an infestation.
White woolly egg masses Photo credit: Connecticut Agriculture Experiment Station, Bugwood.org, retrieved from https://www.dec.ny.gov/animals/7250.html
Want to learn more? Groton has an Invasives Species Committee, learn more here: https://www.grotonma.gov/government/boards-and-committees/invasive-species-committee/
More info about hemlocks and forest succession:
https://extension.unh.edu/resource/hemlock-hardwood-pine-forests
More about the HWA:
https://ag.umass.edu/landscape/fact-sheets/hemlock-woolly-adelgid
https://extension.unh.edu/resources/files/Resource005573_Rep7772.pdf