WINTHROP — When Tracy Robinson walked last week into the Winthrop Commerce Center, she looked neither left nor right and certainly not up.

The five-story, red brick building where she works has been blanketed with thousands of white browntail moths since they began emerging last week from their cocoons across central Maine.

“Oh my gosh, it’s bad,” Robinson said, adding she had never seen so many browntail moths on buildings along Main Street.

If it were a movie, it would be a cross between the 1963 Alfred Hitchcock classic “The Birds,” about the sudden and unexplained attacks by flocks of birds in a coastal California town, and “Mothra,” the giant moth character introduced in the 1961 Japanese monster film that went on to fight Godzilla.

Instead, the emergence of the moths is the final stage in the life cycle of the invasive species that is moving inland from the coast, where it has maintained a population for years.

State officials have said this year is expected to be the worst yet for browntail moth encounters because populations have been in an outbreak phase since 2015. Over the past year, populations have gotten a boost from dry conditions a year ago that limited diseases that would affect the insect during its caterpillar stage.

That is certainly the case in Winthrop.

“They are covering all the buildings on Main Street,” said Robinson, who lives in Readfield.

When Robinson arrived at work at 7:30 a.m. last Thursday, she said the building was covered.

“The building superintendent said he had already swept them off the doors and in the entryway,” Robinson said. “But when you look up above in the entryway, the whole ceiling was covered. And then it goes all the way up to the top of the building.”

When she went to work Saturday, the parking lot was covered with moths that had been hosed off the building.

Tom Schmeelk, an entomologist with the Maine Department of Agriculture, Conservation and Forestry, said the moth hatch this year is more than two weeks earlier than normal.

The moths, which are native to Europe and western Asia, are considered invasive species in the United States. They were introduced in Somerville, Massachusetts, more than a century ago, and they have spread up and down the Northeast coast.

Currently, according to the Maine Center for Disease Control & Prevention, populations exist only along the coast of Maine and Cape Cod in Massachusetts.

The emergence of the moths marks the end of the insects’ life cycle. The moths, which hatch generally at the beginning of July, lay their eggs not long after on the undersides of leaves of oak, maple or other broad-leafed trees. They also target fruit trees.

About a month later, the larval form emerges and starts feeding. By fall, the larvae build nests by binding leaves together with webbing, generally at the ends of branches.

In the spring, the larger larvae start feeding and become more recognizable as the hairy browntail moth caterpillars, with two red dots on their tail ends. In June, they pupate, and in July, they emerge as moths to start the cycle over again.

Their populations are no longer confined to coastal communities.

Reports of the moths have been surfacing across central Maine since the middle of last week when moths began emerging from cocoons.

In Gardiner, where the Maine Department of Transportation’s bridge replacement project is wrapping up, moths have been drawn — by the high-intensity lights that illuminate the work site at night — to Water Street and, for some reason, the Water Street side of the former Key Bank building, at the base of Brunswick Avenue.

In Augusta, where people are reporting moths massing on buildings across the capital city, including at the Augusta State Airport, browntail moth management is now on the to-do list of Earl Kingsbury, the city’s newly appointed director of community services.

In Waterville, the caterpillars were numerous enough this year to prompt city officials to consider applying to the Maine CDC to declare a public health nuisance. That would enable city officials to spend public funds to try to contain the caterpillars on private lands and rights of way.

In Winthrop, Town Manager Jeffrey Kobrock said he has been trying to find a company to treat the town’s trees, but there are waiting lists everywhere.

Robert Long, spokesman for the Maine CDC, said to date, no municipality in the state has sought that designation this year. In 2019, Searsmont and Camden sought it, and in 2018, Yarmouth and Cumberland requested it.

The moths are drawn to light, so it makes sense they are found on commercial buildings, where lights shine all night for safety, security or insurance purposes.

Schmeelk said experts do not recommend using a bug light to attract and kill moths before they get a start on the next generation.

For one thing, mostly males are attracted to the lights, and killing the males would not do much to slow the spread of the population. The lights also attract and kill parasitic flies and wasps that prey on the browntail moths.

Also, people who have tried that method found that because more moths were attracted to lights, more winter webs appeared in their trees, meaning more caterpillars emerge in spring to eventually reproduce unless the nests are destroyed.

“We recommend keeping unnecessary lights outside lights off between 9 p.m. and midnight, from now until the end of August,” Schmeelk said.

That tip and other advice can be found on the state Department of Agriculture, Conservation and Forestry’s browntail moth “Frequently Asked Questions” page.

The moths do not carry the same toxic hairs the caterpillars do on their bodies, their shed skins or pupal cocoons, Schmeelk said, and they pose no health risk to humans.

“We caution that as a moth is crawling out of a cocoon, it could pick up a couple of stray hairs,” he said. “But by far and large, the hairs on the adult moths are not the toxic hairs you need to worry about.”

To control the spread of the insect, Schmeelk recommended residents in affected areas examine their trees on sunny days in December and January — with the sun at their backs — to find the winter webs. Low-hanging webs can be cut out using a pole pruner or hand snips

“You’ll be doing yourself a world of good. Each one of those palm-sized webs contains between 25 and over 400 caterpillars,” Schmeelk said, adding management efforts should be focused on trees that overhang homes or high-traffic areas.

Once the webs are clipped, they can be burned or soaked in a bucket of soapy water, he said.

“You’re also trying to catch the caterpillars before they have caused any damage,” he said, “and before they have grown and have a larger amount of those toxic hairs on them.”

Most chemical treatments are targeted for the last couple weeks of April and the first weeks of May, depending on the type. Injection typically happens at the end of April so the insecticide will be taken up along with water and nutrients.

Spraying the trees has better results when the leaves are out, providing more surface area for the insecticide to reach.

While Robinson has no particular phobia about insects, she’s not planning to look around when she goes to work.

“They’re just going to lay more eggs,” she said. “That’s what I’m thinking of.”

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