MSU Extension asks Macomb residents to report gypsy moth signs

By: Kevin Bunch | C&G Newspapers | Published July 29, 2015

METRO DETROIT — While the invasive gypsy moth has not been a major problem in the metro Detroit area for years, the Macomb County Michigan State University Extension office is asking residents to keep an eye out for signs of the insect’s resurgence.

The gypsy moth is an invasive species from Europe that, in years past, has torn through tree populations in North America, defoliating trees and, in high enough numbers, causing their deaths. Previous outbreaks were handled using pesticides, and every fall, MSU does inspections to see how many egg masses it can find.

The moth has not been seen in great numbers in some time, but Mary Gerstenberger, consumer horticulture coordinator with Macomb’s MSUE, said they have received several phone calls this year from residents who have found egg masses on their properties.

“The last few years when we did the moth inspection, we didn’t find a lot — just a few egg masses, and no residences reported any,” Gerstenberger said. “But this year we had several people who found them and have concerns, so we’re seeing a rise in the immediate population. How big that is, we don’t know.”

MSUE is requesting that people who find gypsy moth egg masses to call them in. Gerstenberger said the masses look tan and are small, about an inch or 2 inches long and an inch wide. Each mass usually holds between 400 and 600 eggs. The masses are usually found in protected areas, like on tree bark, under a tree limb, on wooden rails, on roofs, on siding — maybe even on a car.

“That’s why (researchers) don’t want you moving firewood, and also want you to check vehicles when you go out of the area, because they can be on there,” she said.

Property owners in Macomb County who believe they have found an egg mass can call MSUE at (586) 469-6440 to be included in that fall survey. The egg masses will not hatch until late spring next year, usually around May or June.

Once hatched, the caterpillars will begin eating leaves on the trees — Gerstenberger said oak trees are their favorite, but they will go after the leaves of most trees — and then pupate for about a week or two. They will then emerge as adult moths, reproduce and die.

Oakland County residents who want to report an egg mass can call their local municipality, which will in turn let MSUE researchers know where to look.

Oakland County’s MSUE office has not received any phone calls about the moth, according to Carol Lenchek, coordinator of the office’s gypsy moth suppression program and member of its Natural Sciences Department. She said the last pesticide treatment they were involved in was in 2009 — 100 acres in two areas: around Waterford and in Pleasant Ridge at the Ferndale border.

For such a large area, Lenchek said, they used a helicopter loaded with pesticide to spray the insects from the air. Since then, the population has subsided, and she does not believe any further large-scale intervention will be necessary. Predators, disease and parasites, she said, are the primary drivers of control now.

“So there are parasites — little wasps and such that work on egg masses,” Lenchek said. “There are a lot of different insects that eat them, as well as white-footed deer mice (and) different beetles. The two big ones are two diseases that the gypsy moth get, and the larvae get.”

MSU entomologist Deborah McCullough said diseases are the primary limiter of moth populations, though the effectiveness varies from year to year based on weather. Fungal diseases proliferate if spring weather patterns are conducive for their growth, and while viral diseases are always out there, she said, they tend to be deadlier if the moths are already stressed due to weather or poor food supply.

Predators and parasites do make a dent, but they are less important. She added that trees defoliated by the moths earlier this summer should be able to recover due to the extensive rainfall that southeast Michigan has received.

Residents who do want to get rid of the moths can contact a landscape or pest control company to see if they are licensed to spray for gypsy moths, Gerstenberger said. If an egg mass is close enough to the ground, it can simply be scraped off and put into some soapy water.

If the county decides there are too many moths, Gerstenberger said they would get in touch with local municipalities to see about doing a spray program. The state of Michigan no longer reimburses local communities when they spray for gypsy moths, however, so those municipalities and the county would have to foot the bill.