Terrestrial Invasive Species Information

There are an array of terrestrial invasive species that can influence the health of our water systems.


The tell tale signs of a tree infested with Hemlock Woolly Adelgid : tiny, cotton ball like puffs found on the underside of the needles.

How do forests provide habitat and protect water quality? Often forests provide critical habitat for unique wildlife species because these species of wild trees and animals co-evolved to need each other and to thrive best in association with one another. They form a community.

Two species of trees are currently especially endangered by the spread of invasive species into the Finger Lakes region: Eastern hemlock and ash. Because of the ecosystems they inhabit and the habitat they create, their potential loss should also concern those of us interested in the protection of water quality and natural habitats.

Hemlock Woolly Adelgid

Eastern Hemlocks (Tsuga Canadensis) have been occupying Canandaigua Lake’s gullies for more than ten thousand years, since the last glaciers moved off. Because they like moisture and tolerate shade, hemlocks are considered a “foundation plant.”  They hold the gullies together. They keep the water cooler with their shade, benefitting the trout. They survive where other trees cannot and foster a whole constellation of other plants such as ferns, mosses and lichens that favor the gully conditions.

The Hemlock Woolly Adelgid (Adelges tsugae) was accidentally introduced into the United States from Japan in the 1950s and was first found in the eastern states near Richmond, VA in the early 1950s. The scale-like insect pest which is fatal to Eastern Hemlocks is now established in eleven eastern states from Georgia to Massachusetts. In the Finger Lakes, HWA appeared several years ago on the shores of Cayuga, Seneca, Keuka, Hemlock, Skaneateles and Owasco lakes. In the fall of 2014 it was found near Canandaigua Lake.

The HWA is tiny but can be identified by its egg masses which resemble tufts of cotton on the needle axil. HWA can reproduce twice per year asexually.  It is not very mobile, with larvae emerging in the spring and being spread by wind, birds and mammals

CLWA Program – Hemlock Woolly Adelgid Monitoring in the Canandaigua Lake Watershed

In 2016 / 2017, CLWA received a grant through the Finger Lakes PRISM to fund a program aimed at HWA education and outreach for landowners.


HWA : A brochure for Landowners

HWA locations around Canandaigua Lake

Sources of Information and Help

  • Dr. Mark Whitmore of Cornell University (mcw42@cornell.edu) has a website which offers advice and help on HWA. He needs funding to develop the biological controls that could be deployed to protect the watershed, especially the gullies, of the Canandaigua Lake.
  • Jim Engel, proprietor of White Oak Nursery in Geneva and Canandaigua has a website  with excellent information on HWA and its treatment, including rates.
  • Volunteers could help CLWA to fight HWA in several ways: monitoring for HWA, planting hemlocks, creating hemlock hedges that would be used to raise and distribute Laricobius nigrinus, and monitoring their efficacy. Call our office at 394-5030 to volunteer.

Fact Sheets and Presentations on HWA

Presentations from the December 5, 2015 HWA workshop in Naples:

Fact Sheets:

Volunteer Reporting Forms 

Interested in helping scout for HWA in the watershed?  All you need is a keen eye, some basic ID skills,  and a smart phone to record your GPS coordinates. Check out this handy reporting packet for more information :