The arrival of one of southeastern Connecticut’s most notorious pests is just around the corner. But this year, local tree enthusiasts should rest a bit easier knowing experts are forecasting a much more favorable outlook.

After three years that have brought some of the most devastating gypsy moth outbreaks since the 1980s, with massive defoliation and many tree fatalities in much of the eastern half of the state, the region finally is expected to have put the worst behind it.

“The gypsy moth defoliation last year was very extensive, covering virtually the entire eastern half of the state coming after defoliation in 2015 and 2016,” said Kirby Stafford, entomologist with the state Agricultural Experiment Station. He added that Middlesex, Windham and New London counties especially saw a heavy concentration of the pests. “This year, I would expect much less activity overall.”

However, Stafford did note his department’s egg mass surveys indicate there will likely still be some areas with heavy gypsy moth activity.

First found in Connecticut in 1905, the invasive insects had spread across the state by 1952, and during one of the worst outbreaks in 1981, 1.5 million acres were defoliated in the state. Running on about a 10-year-cycle, the region saw other prominent outbreaks in the late 1980s, in 2005-06 and again in 2015-17.

“2017 was the ultimate ... a taste of back in the old days with the old outbreaks,” Stafford said.

Generally hatching in late April or early May, gypsy moth caterpillars feed on a variety of trees, with oak, apple, birch, poplar and willow trees being among their favorites. Their extensive feeding can cause defoliation, which means stripping trees of their leaves, weakening the trees and in some cases causing them to die.

Despite spring rains breaking a drought and inspiring hope that 2017 would bring fewer of the insects, last year ended up seeing one of the worst of the gypsy moth outbreaks, with more than 1 million acres defoliated across the state.

However, those late rains last year still brought some benefits, which are expected to carry over into this year.

Back in 1989, researchers found that a specific fungus, Entomophaga maimaiga, was killing the gypsy moth caterpillars. Since then, the fungus has been the most important check on suppressing moth activity, Stafford said. However, during the state’s multiyear drought, the number of fungus spores started decreasing because rain is critical for germination.

With the rains last year, the fungus did arrive and killed many caterpillars — but not until just before the caterpillars became moths. That meant the insects already had done most of their damage, Stafford said.

“The fungus came in late, just barely in the nick of time,” he said. “I don’t want to think about if we didn’t have the fungus last year.”

He said there are still many resting spores to help kill the caterpillars again this year, although it would certainly be helpful to get more rain.

“We will still need the spring-early summer rains to get the fungus going,” Stafford said.

But, despite more optimism this year, he still encourages property owners to be aware and on the lookout for egg masses, especially in locations that saw a lot of adult moth activity last year.

He said that spraying is an individual's choice and consulting professional arborists to reach egg masses that are in difficult places is not a bad idea. He also added that, although it is only a small hit on what’s out there, homeowners destroying an egg mass they see certainly doesn’t hurt.

To learn more about gypsy moths, spraying and other possible treatments, visit bit.ly/CTGypsyMoths.

c.clark@theday.com