GAINES TOWNSHIP - After receiving complaints, township officials are looking at potentially conducting a gypsy moth population survey this fall, a step that would be required before a spray suppression program could be undertaken next year.
Township Supervisor Robert DeWard said gypsy moth complaints in Gaines have been heavily localized around the intersection of Eastern Avenue and 68th Street.
After receiving numerous calls from that area and going out to have a look for himself, DeWard got in touch with Neal Swanson, head biologist at Aquatic Consulting Services. Swanson then attended a recent board meeting to provide the Township Board with an overview of his services.
Swanson conducts gypsy moth surveys and recommends spray areas for multiple West Michigan communities, he said, including Wyoming, Kentwood, Walker and Cascade Township.
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"We've been seeing rises in gypsy moths in the last few years," Swanson said. "This is happening throughout West Michigan. A lot of people may have seen (the moths) in person but a lot of people aren't familiar with what they look like or how they got here."
Gypsy moths are an invasive species that were first introduced in Boston in 1905 for the purpose of silk production, Swanson said. Michigan has been generally infested with the insects since 1984, he said, with the early to mid-1990s being a particularly bad period where some forests in the state were seeing up to 90-percent defoliation of their trees.
"As an invasive species, they go through a six-year invasion curve that's kind of standard," Swanson said. "Right now, I would say we're seeing a fairly high peak."
The time frame for spraying for the moths has already come and gone this year, Swanson said, but what the township could do going forward is contract with Aquatic Consulting Services to carry out a population survey this fall.
The survey would produce an egg mass count and identify areas that could benefit from the spraying of Bacillus thuringiensis, or B.t., a bacterial agent that targets the moths' larvae.
"We would do en egg mass count and from that we would say, 'These are areas that have a high likelihood of being an issue come spring and we recommend that area for spray,'" Swanson said. "We provide the maps and consultation on the timing of the spray. The timing of the spray is pretty crucial because you want to make sure that caterpillars aren't too large to be able to survive the spray but not too small when they're not feeding."
Unusual weather patterns the last couple years have altered the time frame within which the caterpillars typically hatch and this has made identifying spray dates in other communities more difficult and less foolproof, Swanson said, which is perhaps the reason officials in Wyoming did not see results that were as effective as they would have liked this year in a particular area of the city.
As an alternative to spraying, Swanson said the township could decide to let nature run its course.
"There are a few predators that will feed on them," he said. "Some mice will eat them, some birds will eat them, but for the most part, the numbers grow unchecked other than the fungus that's called E. maimaiga.
"It's a fungus ... that was actually introduced to control the numbers. And then they have a virus called NPV, which is a density-dependent virus. There's also a parasitoid wasp ... but that's usually about three or four years behind the population."
Swanson said people would be at risk of losing trees without a suppression program, however, as even old, large trees, such as oaks, can easily die from stress after being defoliated for multiple years.
Short of committing to a population survey, which would run the township a few thousand dollars, DeWard said he would have staff call around to other municipalities to get their opinions on the matter first.
"What we'll do is kind of research this further and bring it back to the board with a recommendation," DeWard said. "It's pretty localized right now in, I would say, probably about a half square mile.
"The other argument would be to let nature run its course but ... if it does explode and take off and you haven't done anything, were you negligent by not requiring them to spray? Those are just the kinds of questions we would be asked."