View full sizeA gypsy moth caterpillar.BAY CITY, MI —
Our unseasonably warm spring has brought out the gypsy moths earlier than ever before.
This year they were spotted in Pinconning around April 14 or 15, the earliest date recorded in Bay County, said Alicia Wallace, Bay County gypsy moth suppression program coordinator.
"We usually see gypsy moths in the beginning of May," she said. "The earliest we've ever seen them before is about the 24th or 25th (of April)."
The caterpillars' latest local appearance was May 23, in a year with a cold spring.
"We've had such an early spring with the weather," Wallace said, explaining that the larvae depend on the air temperature to develop. Insects have to have so many days over 50 degrees accumulate, in what are called "degree days."
"It's what makes trees' leaves come out when a certain amount of heat accumulates in the tree," she said.
The gypsy moth population is still extremely low. In areas with eggs, residents may see 1/8-inch caterpillars crawling around. When they first hatch, they climb to the highest point they can reach and wait for the wind to blow them to a new area.
"Their favorite trees are oak and poplar, but they'll pretty much eat anything but the ash tree," Wallace said.
Oh, the irony. The otherwise durable ash tree has its own enemy, the emerald ash borer. She expects those adults to appear in the next week.
Leaves are coming out on ash trees now. Last year was more typical, with leafing the second week of May.
The early spring helps the gypsy moth suppression program, Wallace said. With maples and oaks leafing out now, the point at which they are developed enough for treatment is earlier as well.
Saginaw County does not have a gypsy moth program and does not monitor, but staff with the Saginaw County Mosquito Abatement Commission said they would not be surprised if gypsy moths were appearing early there because the "odd spring" had brought mosquitoes out early.
Bay County residents who feel the gypsy moth population on their property is increasing or have questions about invasive insects can call Wallace at 895-4195 to have their area surveyed.