NORTON SHORES, Mich. (WOOD) — Parks officials in Norton Shores have arranged two treatments for a shoreline park dealing with an invasive species.

Brian Clark, the Norton Shores Parks & Recreation superintendent, told News 8 that pesticide treatment will start this fall in Lake Harbor Park to treat hemlock trees infested with the hemlock woolly adelgid.

Drew Rayner leads the Michigan Department of Natural Resources’ fight against the tiny bug in West Michigan. He said the insect can’t move quickly on its own but has managed to stretch across five different counties after first being spotted in 2015.

“It only exists right now from Allegan County up to Mason County. So we really have about a five-county area and it really hugs the shoreline,” Rayner told News 8.

The hemlock woolly adelgid spreads primarily by hitching rides off other animals and humans.

Several dying hemlock trees in Lake Harbor Park spotted on July 25, 2022. DNR expert Drew Rayner says the hemlock woolly adelgid is the likely cause. (Matt Jaworowski/WOOD TV8)

“There’s a lot of vectors,” Rayner said. “Animals can spread them; birds and wildlife can pick up crawlers. We have crawlers from spring through the early summer that we aren’t really going to be able to see (when) humans and animals brush up against the branches of an infested tree.”

The most common sight isn’t the insect itself but what it produces.

“When HWA feed, it produces a white ovisac, a little white, cottony mass. You’ll see them lined up right at the base of the needle,” Rayner said. “It’s easiest to kind of flip some branches over and look at the bottom side of the branches. … It’s pretty easy to spot.”

Because the HWA are pulling nutrients from the trees, the hemlocks stop growing and its needles develop a grayish tone. But with treatment, the insects are killed and the trees can recuperate.

When hemlock woolly adelgid feed, the leave behind a small, white cottony ball called an ovisac that forms at the base of the needles. (Matt Jaworowski/WOOD TV8)

There are two treatments to kill off HWA: One that can be applied to the tree bark and another that is sprayed at the base of the tree and absorbed through the roots.

The bark treatment is effective but it takes a long time to take hold. The soil drench treatment takes effect quickly but wears off quickly and can cause chemicals to leech into the groundwater depending on the soil content.

“There’s basal bark applications where you’re mixing the chemical in a sprayer and you’re applying the chemical onto the bark. It’s pulled in through the bark and moved up to the tree,” Rayner said. “And then soil drenches mix the chemical in water and are poured at the base of the tree. We’ve been trying to stay away from soil drenches here in Michigan because we have a really sandy soil along the coastline. … It really depends on the condition of the tree.”

According to the DNR, Michigan is home to more than 100 million mature hemlock trees, which provide an important habitat and coverage for wildlife during the winter.

Work at Lake Harbor Park is expected to start in September. Crews will start with 28 acres of land near the southern part of the park. Crews will return next year to treat another 39 acres on the northern half of the park.

This fall’s work is expected to cost approximately $28,000. According to Clark, the funding was secured during the annual budget process in May.

If you spot a tree that you believe is infested with HWA, do not remove the material. The DNR asks you to take photos and note the location of the tree, then submit the information to the agency. You can learn more about HWA through the DNR’s website.