After tormenting residents of the midcoast for several summers, browntail moth caterpillars have arrived in the heart of Portland.

Alan Bennett of Portland shows one of the rashes he believes were caused by contact with browntail moth caterpillars. He said, “It looked like really bad poison ivy, and it got red and scaly a little bit.” John Ewing/Staff Photographer

Deering Oaks is suffering a “light infestation” of browntail moths and a handful of visitors to the park have reported the bumpy and itchy rash caused by airborne hairs from the caterpillars, city officials said. The caterpillars also eat leaves and are seen as a potential threat to the park’s historic oak trees.

The moths are in the caterpillar stage of their life cycles now, shedding tiny hairs that become airborne and trigger reactions that can be severe for people who are sensitive to the effects. The hairs can cause skin rashes and, in some cases, breathing problems if they are inhaled. Portland parks officials have posted signs alerting visitors to the problem, but said they don’t believe it’s serious enough to warrant closing all or parts of the park.

The moth population has spread in recent years from midcoast Maine into the northern suburbs of Portland, primarily affecting coastal communities. Portland is still at the edge of the infestation, although Falmouth is now in the high risk area for health effects, according to the state Department of Agriculture, Conservation and Forestry.

In the next two to three weeks, the caterpillars should change into moths, after which they will no longer pose a threat to people.

City staffers noted the moths’ webs in the park’s oak trees this past winter and removed as many as they could reach, but some were higher than the 70-foot bucket truck that was used, said Ethan Hipple, deputy director of Portland’s Parks, Recreation and Facilities Department. He said the city injected affected trees with insecticide and conducted some limited aerial spraying this spring to try to kill the insects in the webs they couldn’t reach.

The problem is worst near the center of the park, with infestations in some of the park’s oldest oaks, Hipple said. If the infestations persist, the caterpillars eating leaves could kill some of the trees, he said.

“They really like oak trees,” Hipple said. There have been no reports of browntails in other city parks, he said.

A park support group, Friends of Deering Oaks, posted a warning about the browntails on its Facebook page.

A browntail moth caterpillar. Maine CDC photo

Ann Pringle, the organization’s president, said the group is concerned about both visitors’ health and the impact of an infestation on the trees.

“We don’t want to lose 200-plus-year-old oak trees,” she said.

Pringle said she dealt with an infestation a few years ago near her summer home on Little Diamond Island, where a couple of neighbors got a rash from the caterpillar hairs. One developed severe breathing problems, she said, so she’s aware of the health threat posed by the tiny hairs.

“It’s a terrible problem, it really is,” she said.

The location of the densest concentration of caterpillars means that the park playground and splash pool could be affected, possibly exposing children to the caterpillars’ hairs, Hipple said, and most of the warning signs have been posted in that part of the park.

Hipple said three people have contacted the city to say they got rashes they believe were caused by caterpillars in the park.

One was Alan Bennett, an official with the University of Southern Maine, who said he and a couple of friends developed rashes after visiting the park two weeks ago.

Bennett said he didn’t notice any hairs in the wind while he was at the park, but a bumpy rash developed on both of his arms and the back of his neck as he was walking to his home on the city’s West End. A friend told him she developed a similar rash and suspected it was caused by browntails. Bennett said he passed that suspicion on to his doctor a few days later and the doctor immediately said it was a browntail rash and prescribed prednisone, an anti-inflammatory steroid.

“It looked like really bad poison ivy, and it got red and scaly a little bit,” he said.

The prednisone helped, Bennett said, but the rash has gotten worse in the past few days after the prescription had run its course. He’s using cortisone cream now to control the itchiness, Bennett said, and “it’s not unbearable the way it was before.”

Bennett said he used to enjoy jogging in the park, but plans to avoid it for a while.

“I’m definitely not going to Deering Oaks (soon),” he said. “I’ll go in the fall.”

Parents who gathered in the park Friday afternoon as their children played in the Ravine Pool near the center of the park said they had not noticed any ill effects.

Christy Reed, 36, said she saw a warning on Facebook, but it did not factor into her decision to come and let the kids splash around.

“I have not seen anything and don’t know anyone personally who has,” she said.

Browntail moth infestations are cyclical, driven by weather conditions. The moth has no natural predators, but a wet spring can allow a fungus to infect the caterpillars, causing die-offs.

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