Come along as teams hunt a tiny bug that threatens Michigan’s hemlock trees

 

(Today’s MI Environment story by Zoi Goss, of the Michigan Department of Natural Resources’ Forest Resources Division, is courtesy of the DNR.)

Well before sunrise on a Wednesday morning, I got up to make the journey from Lansing to Ludington to survey trees for an invasive insect known as hemlock woolly adelgid. The weather was in the 40s with a chance of rain, which, thankfully, held off until my drive home that afternoon.

At the site, I met up with a four-person crew from the West Michigan Conservation Network to get started surveying the woodland outside of West Shore Community College near Ludington.

Surveying means going through the woods to check each hemlock tree for signs of the tiny, invasive insect. If found, each infested tree is tagged and recorded for later treatment.

The crew I joined for the day is based in West Michigan, and they are called to check private and public lands for any signs of infestation. They have been in the woods all winter, checking new sections of hemlock forest for the adelgid, and I was able to join them to learn more about the process and what this insect is exactly.

Even though it was 40 degrees, snow still covered the ground, up to my knees in some spots! It was very pretty to be hiking around snow-covered trees and hearing the woodpeckers tapping above us in the branches.

We had been hiking through the woods for a few hours that morning, double-checking some trees that were marked as positive in a previous survey, but we hadn’t found any positive identifications.

Just as I was remarking that finding evidence of an infestation would be bad, but good for my article, one of the team members grabbed a branch and turned it over to look at the underside of the needles.

There it was – one tiny hemlock woolly adelgid attached to the branch and covered in its white protective mass. I had never seen a hemlock woolly adelgid – or any type of adelgid – in real life. It was interesting to see the team identify it and differentiate it from other, similar insects such as spittlebugs by examining the white covering.

What is this insect?

Hemlock woolly adelgid, or HWA, is an invasive species that was first confirmed in Michigan in 2006 and is currently found in 11 counties, mostly along the Lake Michigan shoreline.

This insect moves from tree to tree, transported by people, birds, animals or the wind. Once on a tree, it feeds on the sap of young branches at the base of needles.

This little thing is less than 1/16 inch long, nearly invisible to the naked eye and found most commonly in its mature stage, with a white, woolly, waxy protective covering that makes it stand out against the branch.

Adelgids lay their eggs on the branches and feed on the sap through the winter and spring. In summer, an infected hemlock experiences reduced branch growth, premature needle dropping, dieback and eventually death.

HWA is especially threatening to Michigan because the state is home to over 170 million eastern hemlock trees. These trees create shelter for birds and animals, stabilize soil near streams and regulate microclimates for fish and animals throughout the year.

Hemlock woolly adelgids currently affect over 20 states across the United States and at least two Canadian provinces.

Battling HWA takes teamwork

The Michigan Invasive Species Program, a joint effort of the Michigan Department of Natural Resources and the Michigan departments of Agriculture and Rural Development and Environment, Great Lakes and Energy, continues to work with Michigan State University and multiple local cooperative invasive species management areas, or CISMAs, to prevent the northward spread of HWA and protect high-quality ecosystems, including those in state parks along the Lake Michigan shoreline.

These groups work together to manage HWA by surveying forest sites during the winter to determine which areas are affected. Winter is the best time to survey because HWA is less likely to be spread to other trees in the area from human movement, and the egg masses are most visible in the winter.

The trees infested by HWA are treated in the summer, when the sap is flowing. Insecticide is injected into the sapwood of larger trees or sprayed onto the trunks of smaller trees.

The insects ingest the insecticides through the sap, and there is virtually no damage to the tree or surrounding plants. The treatments are effective for five to seven years.

Going out in the field is always exciting for me, as I spend most of my days behind a desk. I am not sure what I was expecting, but working in the field with the West Michigan Conservation Network HWA crew was a lot tougher than I thought.

Walking around for hours through the woods is so serene and peaceful, seeing all the trees covered in snow and guessing which animal left which prints behind. However, hiking through the snow is no easy task.

While I was tired and sweating, the crew was working along with no problem, enjoying themselves and surveying the trees. The work that they put in each day to protect our trees is incredible.

The team of four had a system figured out.

One person measured the trunk of the tree being examined to see how many holes they will have to drill in the spring. Another person tagged the tree with a number to catalog it. And yet another person checked the branches for HWA, while the fourth team member recorded all the information on an online survey data app.

The team is called to check sections of public and private lands in areas that are at risk for HWA.

There are treatment options for the insect and ways to help prevent its spread as well.

On your own land, you can prune branches that might hang low enough to hit vehicles driving by or parked underneath, as the insects can be transported long distances by vehicles.

You should clean your vehicle after traveling to make sure you do not accidently transport any invasive species. Cleaning your boots and equipment is another way to prevent accidental transportation. 

If you think you see HWA, take a photo and report it so it can be identified, and action can be taken if needed.

Invasive species like HWA are everywhere and can be extremely dangerous for Michigan’s ecosystems.

We can continue to help fight against them with the help of CISMAs across the state and other DNR partners. You can help by being aware of the signs and symptoms of invasive species invasion.

The DNR and the Midwest Invasive Species Information Network have information on identifying and reporting different invasives.

It is better to be safe than sorry – if you think you see an invasive species, take pictures and report it right away. Find more information on species identification and reporting at MISIN.msu.edu or Michigan.gov/Invasives.

After my day in the woods with the survey crew, I got home that night and was exhausted. I got in all my steps and had sore legs to prove it for the next few days.

Being in the field is the best part of my job. I get to more fully understand and appreciate Michigan’s natural resources and the people whose job it is to protect them.

This trip was also fun and informative because you always hear about all these invasive species, but you don’t always get to go out and see them up close, nor do you get to accompany the people who are fighting their spread and destructive impacts.

Going forward, I am now looking forward to learning about more invasive species and what we all can do to battle them.