Frequently Asked Questions (FAQ’s)

1) Can you tell me more about why hemlock conservation is so important?

New York State has more hemlock trees (Tsuga canadensis) than any other US state. They are the third most common tree in the state and serve as a foundation species, meaning they create unique ecosystems and carry out important ecosystem services that we, as well as numerous wildlife species, benefit from. Hemlocks help keep water resources clean, provide ecologically important habitat and are the base of the food web for many species, stabilize soils on steep slopes for erosion control, and are a beautiful tree characteristic of New York’s forests. The loss of hemlock trees on a large scale would be devastating for the state of New York, so it is vitally important that we take steps to address threats to hemlocks now and for the future. Hemlocks are also very slow-growing, shade tolerant trees. Even without inhibiting factors such as deer herbivory and competition from native and invasive plants, the recovery of hemlock dominated habitats will take many, many years. You can learn more about hemlocks and the threat from hemlock woolly adelgid (HWA) here.


2) My favorite natural area has trees that are infested. What can I do?

You can report hemlock woolly adelgid (HWA) infestations in one of the following ways:

1. You can call the DEC’s forest pest information line at 1-866-640-0652. The line is staffed during business hours but you can always leave a message notifying the DEC of your sighting.

2. You can use the iMapInvasives smartphone app. Don’t have the app? Find it at, on iTunes and the Google Play store. Once you have the app, request a log-in and check out the online trainings that show you how to report invasive species through iMap. iMap has both HWA and “x-HWA”, meaning no HWA found. Whether you find HWA or not, report it in iMap! You may also use the desktop version if they don’t have a smartphone.

3. You can report to us using our survey form. You can visit our “Report HWA Finding” link which includes instructions on how to fill out our HWA survey form and email or mail it to us.


3) I want to treat the hemlocks on my property. Where do I find a certified pesticide applicator?

Go to our Pesticide Applicators page to find information on finding a certified applicator and pesticide use for HWA. We do not do pesticide applications at the NYS HI, but are happy to offer advice regarding application methods. More information on HWA management strategies can be found here.


4) My hemlocks are growing near water; can I still treat them?  How?  Will treating my trees hurt the stream/lake/pond life?

Current research has shown that pesticide treatments are not very mobile in soils, so the risk of off-target impacts is low. Ultimately protecting the hemlock resources in a given area is critically important for maintaining the habitat integrity overall. For more information including recent research findings and descriptions of the methods available for HWA management, click here.


5) I don’t yet have HWA on my trees. Should I treat them preventatively?

Preventative treatment is not advised. After initial infestation of HWA, it may take between 4-15 years for the tree to die if no action is taken. Even very heavily impacted trees may recover quickly after proper treatment depending on the health of the tree and other stressors. Often it is better to conserve your resources and treat your trees on an as-needed basis. It is also important to note that current treatment practices have only been found to be effective for about seven years.  More information can be found here.


6) How does the NYS Hemlock Initiative fit in with other groups that manage hemlocks in New York? Does DEC know about your program?

We partner and collaborate with many local, state, and federal groups to combat the spread of HWA in New York. While we are based at Cornell University in Ithaca, we work especially closely with the DEC throughout the state; they collect statewide HWA data, conduct may treatments for HWA, and help fund our programs in detection, outreach, and biocontrol research. In addition to the DEC, our funding comes from the US Forest Service, the US Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS), and The US Environmental Protection Agency’s Great Lakes Restoration Initiative (EPA-GLRI). We are also partnering with local and regional groups like land trusts, colleges and universities, watershed groups, and individual volunteers to strengthen our network.


7) I’ve heard you’re looking for hedges and I have one. What would you use it for? How would that work?

We are currently researching and breeding biocontrol insects to serve as predators of HWA. Our hope is to release these predatory insects at infested sites to control HWA populations and prevent hemlock die-off and decline. The biocontrol insects need food supplies to grow and thrive before release, and we don’t have enough space or food resources to care for the populations we anticipate in our rearing facilities. One way we are solving this is by rearing predatory biocontrol populations on HWA-infested hemlock hedges throughout New York so that we may collect and release healthy biocontrol populations once they are ready to move. While we cannot guarantee biocontrol insects to everyone, we are willing to look at your hedge and determine its suitability for our needs. If you are interested in finding out more about our “biocontol insectary” hedge program and biocontrol insects in general we have resources available here.


8) I want to plant a hemlock hedge for the biocontrol field insectary project.  How does that work?

That’s great! We would suggest that you talk to us before planting a hedge to see if your site is a good fit for the biocontrol program. If you decide to plant a hedge we have planting and growing tips available here. If your hedge thrives and becomes infested with HWA, it will become a candidate to be a field insectary (please note that given the difficulties of biocontrol collection and rearing we cannot guarantee bicontrol insects to everyone).