Browntail moths, whose invasive caterpillars have tiny rash-causing hairs that strike fear into Maine summers, did not have a good year here.
The state found the caterpillars seemed to have had a more “sporadic population” across the state this year than in the past, a Maine Forest Service newsletter said on Thursday.
They were recorded in more than 46,000 acres of the state in 2023, and harm forests as well as humans.
Their more scattered populations this year are likely because of pathogens that attack the caterpillars, the state said. Last spring and summer, wet conditions helped those pathogens spread, and conditions this year let them continue to affect the caterpillars, according to the forest service.
With the right weather conditions in future seasons, they could still rebound in areas where they died off.
The state surveys trees from the air each year to record damage to leaves done by the caterpillars. Early this spring, surveys found 2,000 acres where leaves were damaged by the caterpillars, a significant decline from previous years. In 2022, the height of the population boom, 250,000 acres of damage was recorded.
Bangor’s Public Works department, which monitors adult moth gathering places, reported in late July that they found fewer than a dozen moths in total among places that had hundreds last year.
It became more difficult statewide to see where the caterpillars had eaten through parts of the leaves later in the season because the leaves turned early as a result of dry weather, the forest service said.
When the leaves fall, you can survey your trees yourself for signs of the caterpillars such as their winter webs. That will help you plan to destroy them in early winter by cutting them out of your trees between October and mid-April, when the caterpillars emerge.
You can also have your trees professionally injected with chemicals that kill the caterpillars.
