Hemlock groves are found only in the Three Lakes region of Lewisboro where they cover almost 500 acres along the south shores of Lake Waccabuc and Lake Oscaleta. Eastern hemlocks, along with red cedar are our only native evergreen trees (white pines grow further to the north and the Norway spruce growing around our reservoirs were planted). Hemlocks are one of the most ecologically important tree species in the northeastern forests. Because they are extremely shade tolerant they can grow in riparian (stream) areas, in shaded ravines and along the edges of swamps where they keep the temperatures cool for trout and other fish. Their roots prevent stream bank erosion and help to purify stormwater. In the winter, when other trees have lost their leaves, they provide thermal protection for wildlife. And during the rest of the year, the hemlock is a place for birds to nest or roost. In fall and winter its seeds are a valuable food source for wildlife. Hemlock trees provide food through their seed cones and habitat for more than 90 species of birds and mammals including kinglets, chickadees, nuthatches, brown creepers, black-throated blue warblers, pine warblers, blue-headed vireos and great horned owls as well as red and flying squirrels.
Yellow lady slipper orchids had grown beneath the hemlocks in Three Lakes, though they might have been eliminated by wide-spread deer browsing.
Hemlocks are extremely long-lived and local naturalist Ken Soltesz has estimated that some hemlocks in the Three Lakes are 600 years old!
Watch this short video to learn more.
Look out for
The wooly adelgid! As is the case across the United States, our hemlocks are suffering from the wooly adelgid infection caused by the non-native aphid that first appeared in Connecticut in 1992. It is predicted that the wooly adelgid will overwhelm the majority of the eastern hemlocks in the eastern United States, threatening this keystone species with extinction! Many hemlocks are already dead and many others are thinning in the Three Lakes region. No hemlocks show resistance to the insect. The long term hope for saving hemlocks rests in biocontrol – that is the release of insects that naturally prey on the wooly adelgid in their original location in Asia. If you are fortunate enough to have a hemlock on your property, you can protect it from adelgid infestation by applying a dormant spray oil.