Shelby partners with Macomb MSU Extension to control gypsy moths

By: Kara Szymanski | Shelby - Utica News | Published April 15, 2019

 According to the Michigan State University Extension, although the gypsy moth caterpillars do not kill the trees, they cause trees to use what should be the next year’s energy reserves to regrow leaves.

According to the Michigan State University Extension, although the gypsy moth caterpillars do not kill the trees, they cause trees to use what should be the next year’s energy reserves to regrow leaves.

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SHELBY TOWNSHIP — The Shelby Township Board of Trustees unanimously voted to partner with the Macomb Michigan State University Extension to help control gypsy moths in the county at its April 2 meeting.

The project is planned to happen in mid-May in Shelby Township in the residential area of Van Dyke Avenue at 23 Mile Road, where an infestation was found. The area that will be sprayed, which is approximately 98 acres, spans from 23 Mile south to Devon Drive and goes east to Otter Creek Drive.

The board budgeted for the project not to exceed the cost of $20,000, which will come from the general fund.

The effects of a gypsy moth infestation can lead to a number of issues.

“Many of you may have noticed the damage done by the gypsy moth caterpillar, created as they chew on the leaves and create a Swiss cheese appearance. The impact on the trees is devastating,” said Shelby Township Supervisor Rick Stathakis.

According to the Michigan State University Extension, although the gypsy moth caterpillars do not kill the trees, they cause trees to use what should be the next year’s energy reserves to regrow leaves.

This can lead to the trees not having the energy to grow that they should the next year.

Terry Gibb, who has been in charge of the gypsy moth program at the MSU Extension since 1992, presented the topic at the Board of Trustees meeting.

“It’s a foreign pest that was introduced back into the United States in 1869 in Massachusetts, and it has continued to spread ever since then. We’ve had a program in the county ever since 1990, but we haven’t actually sprayed since around 2009 because there are some natural predators that have kept the populations low,” said Gibb.

She said that unlike in other years, this year the predators have not been able to keep the moths under control.

“Unfortunately, that is not the case this year. We have two communities that have significant infestations, that if we’re going to do something and try to keep these populations down, we need to deal with it as we do it. Macomb County is a little different from other counties in the state, as well as other states, in that we don’t have huge, thousands-of-acre tracts that need to be sprayed. We have hot spots, and it could be 50 acres, 100 acres, 200 acres, but they are hot spots because of the way our development patterns are,” said Gibb.

She said that the extension will be using Bacillus thuringiensis, commonly called Bt, which is naturally found in soil. This bacterial insecticide kills caterpillars that eat it within a week of its application. The insecticide is nontoxic, safe for pets, wildlife, beneficial insects and humans, according to Gibb. It specifically targets gypsy moths.

She went into more depth about what exactly happens to the trees when the caterpillars eat the leaves.

“Basically, what happens is the caterpillars eat the leaves. If they eat at least 40% of the leaves, the tree will releaf again the same year, but unfortunately, when it does that, it’s using next year’s energy reserves to do that. Gypsy moth does not kill your tree. What it does is it weakens the tree, stresses it, so that other predators and other things can get to the tree, and that’s what kills the tree. It’s not gypsy moth — gypsy moth just sets the stage.”

She said that moths can lay their eggs in many places that people wouldn’t think of and that people might not even see them at all.

“Last August, the moths laid their eggs, and they lay them in all kinds of places. Not to point fingers, but actually Macomb County had their first gypsy moth infestation here in Shelby Township off a snowmobile. They can be on the crooks of trees; they can be under your gutters; they can be any place where they think it’s safe for them to lay their eggs and they’re out of the way so you don’t see them. That happened last August. After they lay their eggs, the moths die and nothing happens until we get to April of this year. Well, we did our surveying, obviously, and found them.”

Gibb shared the process the moths take to develop.

“So what will happen is that depending on weather, somewhere hopefully between late April to mid-May, the eggs will hatch. Each one of those eggs is about a quarter size if they’re good. Healthy egg masses will have anywhere from 150 to 1,000 eggs in there. Each one of those eggs will become a new caterpillar. So that’s a lot. Within a few days, they’re going to start moving up the tree. They’re going to feed on the trees unless they’re stopped.

“About mid-July to mid-August, they wrap themselves in a cocoon, and that’s when they are pupa phase, and then they will come out as the moth. The females do not fly, but they give off a pheromone that attracts the male, and the male does fly. And the males have been known to fly many miles to get to the female,” Gibb said.

She said that the entire process from egg to hungry caterpillar only takes a short time, and the destruction of a tree doesn’t take long either.

“All of that takes about two weeks. It really isn’t a long process, but it is a very devastating process because two things: We have the destruction of the trees, but second of all, we have the nuisance factor — especially when they’re in the caterpillar stage,” Gibb said.

The caterpillars not only go up and down the trees, but they can be on the ground too.

Gibb said that years ago, MSU Extension officials went to a location where they saw them all over the place.

“We literally could not walk up the driveway. We were stepping on them. ... They were hanging from trees and on the windows,” she said.

The Macomb MSU Extension said it will be conducting an aerial spray either by helicopter or by fixed-wing aircraft, and that it will begin the project at first light on the planned day.

Gibb said the project will be done depending on many factors, such as humidity and temperature.

The spraying takes 10 to 15 minutes, and everyone will be notified by mail when it will be occurring.

The Macomb MSU Extension will provide contact information for residents who have questions. For more information, call the township at (586) 731-5100.