It is one of the largest and most recognizable trees in Maine, and it’s a bellwether for the suffering that many other trees are experiencing as a result of invasive insect infestations and lack of rain in recent months.

The beautiful and beloved Candelabra Tree, as it is widely known, is a sprawling pin oak at the edge of Deering Oaks, a 55-acre park in Portland. It lost 90 percent of its foliage when it leafed out in early May, ravaged by browntail moth caterpillars despite the city’s efforts to control the infestation.

Winter moth and gypsy moth caterpillars have been on the attack elsewhere in Maine, aided by abnormally dry weather that has caused moderate drought conditions to expand across 40 percent of the state in recent weeks, according to the U.S. Drought Monitor.

The Candelabra Tree has since put out a modest second flush of leaves, and City Arborist Jeff Tarling is stepping up insect control measures to protect a tree that is ogled by many motorists who drive through the park on their way to Forest Avenue

The city also is set to resume holding events in Deering Oaks, including the weekly farmers market that will be back in the park this Saturday. It was held in Payson Park for the last few weeks while Tarling and his crew got the browntail moth infestation under control in most other trees in Deering Oaks.

But the estimated 100-year-old Candelabra Tree, whose robust and graceful shape is dressed in holiday lights each year, is still pitifully bare compared to its usual lush canopy. And it’s under continued assault by the hairy brown caterpillars that also plague people with skin rashes and breathing problems. Some concerned residents have called Tarling’s office, wondering what’s wrong with the treasured tree.

“Thousands of people drive by this tree every day,” Tarling said. “People are concerned because they see what’s happening, and I’m concerned because I don’t want to lose a beloved tree. It’s definitely on the danger list.”

The Candelabra Tree is listed on the Maine Register of Big Trees, where it’s recognized as the largest known pin oak, likely planted around 1920. With a trunk circumference of 163 inches and a height of 89 feet, it is surpassed by other trees on the list that exceed those dimensions. But it has the widest crown spread of any tree on the register, with branches stretching 106 feet across.

A browntail moth caterpillar, with its distinctive two red dots, climbs the bark of the Candelabra Tree in Deering Oaks, one of the most recognized and largest trees in the state. Ben McCanna/Staff Photographer

Its extreme crown spread likely played a role in the tree’s nearly complete defoliation last month and its limited second leafing, which appears spotty in the outer reaches of its branches.

Tarling’s six-person forestry crew removed thousands of webby browntail moth nests last fall and this spring from trees throughout Deering Oaks. In early May, they injected a systemic pesticide into the roots of 50 prized trees among about 1,000 overall in the park, including the Candelabra Tree.

They also sprayed an organic insecticide that targets caterpillars on many infested trees throughout Deering Oaks. His crew applied the pesticide before dawn in the third week of May, when there was little wind and few people were in the park. But Tarling stopped short of spraying the Candelabra Tree because it’s so close to High Street as it passes through the park.

Trees that were sprayed appear to have experienced little defoliation.

“We’ll probably spray (the Candelabra Tree) as well next year,” said Tarling, who oversees the care of nearly 20,000 trees citywide.

The browntail moth is only one of the invasive insects and other factors harming trees in Maine, which is ranked the most forested state, where more than 90 percent of land area is covered by trees, according to a federal forest inventory. But browntails are among the most noticeable and troubling to humans.

Portland City Arborist Jeff Tarling points out injection sites at the base of the Candelabra Tree in Deering Oaks. Tarling’s forestry crew injected the tree with a systemic insecticide to target a browntail moth caterpillar infestation. Ben McCanna/Staff Photographer

Seen only in Maine and Cape Cod, Massachusetts, browntail caterpillars have devastated trees across southern, midcoast and central Maine. Their toxic hairs cause a skin reaction, either from direct contact or airborne hairs, that is similar to poison ivy and can last from a few hours to a few weeks, depending on a person’s sensitivity. People who breathe in the hairs also can experience trouble breathing.

Winter moth caterpillars are also defoliating trees on Peaks, Cushing, Chebeague, Great Diamond and Little Diamond islands in Casco Bay, Harpswell, the Boothbay Region and Mount Desert Island.

However, Cape Elizabeth – previously a center of winter moth activity – saw limited defoliation this spring after years of intensive control efforts, including repeated releases of parasitic flies that interrupt the moth’s life cycle, town officials said.

Gypsy moth caterpillars, meanwhile, are turning hillsides brown in Brownfield, Fryeburg, Lovell and other towns throughout Oxford, Franklin, Somerset, Piscataquis, Penobscot and southern Aroostook counties.

Invasive moth populations have been especially successful this year because abnormally dry to moderate drought conditions in May and June diminished the growth of fungi and other environmental factors that usually tamp down caterpillar activity, said Allison Kanoti, state entomologist with the Maine Forest Service.

“That’s part of the reason caterpillars are behaving badly,” Kanoti said. “In some areas drought has been hitting trees year after year.”

Lack of rain is a double whammy, Kanoti said, because it also weakens a tree’s ability to produce leaves and fight insects and disease. Other challenges such as pollution, climate change and deforestation are taking their toll as well.

Webbing on the underside of a branch of the Candelabra Tree in Deering Oaks is where browntail moth caterpillars are pupating into moths that will emerge in July. Ben McCanna/Staff Photographer

Kanoti said homeowners and others can help by monitoring nearby trees and reporting damage to the forest service. They also should buy firewood that’s harvested locally to avoid spreading invasive pests, such as the emerald ash borer, and damaging diseases, such as beech leaf disease.

People also can provide supplemental water during dry stretches, soaking the ground around ornamental shrubs and trees once or twice a week. That’s what Tarling’s crew is doing, getting a head start on what could be a dry summer by watering 20 to 40 trees a day.

They’re focusing on younger trees with shallower root systems and paying special attention to precious older trees, including the Candelabra Tree, which has a thick mulch ring at its base to help retain moisture.

“We’ll be watching it closely,” Tarling said. “The next eight weeks are usually the driest weather of the year. We’re already gearing up for July and August. You don’t want to wait till the leaves are dry and wilting or falling off.”