A March 4 presentation on Browntail moths by State Forestry Service Entomologist Tom Scheelk brought Camden residents ready to battle the invasive pest by destroying or removing its winter webs.

Mechanic pruning is the one solution experts and community members in the audience agreed can be used now to kill nesting caterpillars. An experimental project using drones to destroy the nests raised interest. Other ideas such as blasting out nests with shotguns, using drones to burn nests in treetops and aerial spraying of pesticides were debunked as ineffective or too dangerous.

Schmeelk told Select Board members that Camden, Rockport and Lincolnville are on the "leading edge of infestation."

Winter webs made of leaves wrapped with Browntail moth silk, no bigger than a hand, can contain from 25 to 400 caterpillars, he said. The webs are visible at the tops of trees, particularly when the sun shines on the silk, he explained.

"The number of webs are high," he said. "You are experiencing the huge population for the first time."

Schmeelk said coastal towns to the south have gone through this, and over time a fungus that kills Browntail moth caterpillars knocked down populations in those areas.

He explained that the fungus grows during cool wet spring weather, and once it kills off a number of the caterpillars, the decaying pests become a host for more production of the fungus. That cycle has not had time to occur in Camden and surrounding areas, he explained.

When asked if the fungus can be produced and then sprayed on the webs, and what else it might kill, Schmeelk explained it is difficult and would cost millions of dollars to weaponize the fungus.

The Forestry Service cultivates a similar fungus that kills Gypsy Moth caterpillars, which involves growing the fungus on the caterpillars and liquefying the pests, as an ingredient in the spray, he explained.

The fungus that kills Browntail caterpillars, while similar, is "extremely difficult to cultivate" and the caterpillars are difficult to grow in captivity, Schmeelk said.

He advised pruning out webs that can be reached, and burning them or soaking them in soapy water, before mid-April of May when the caterpillars come out of their webs. Most webs that can be reached by homeowners would be in fruit trees or smaller trees, he said. Protective clothing and gear should be used, even in the winter, by people who are sensitive to the caterpillars toxic hairs, he said.

Schmeelk also recommended hiring licensed arborists and those who are licensed pesticide applicators, and said the State Forestry Service website maintains lists of these professionals on its website.

He advised against mass aerial spraying, stating that it will not work in Camden, because the spraying is not allowed in buffer zones around waterways including lakes, rivers and the Penobscot Bay. Residents can also choose to opt out of having their properties sprayed, and buffer zones around those opting out also cannot be sprayed.

Town Manager Audra-Caler Bell said she has been speaking with managers of towns south of Camden, and they explained that aerial spraying does not work because the buffer zones and properties opting out create "a swiss cheese effect."

Planning and Development Director Jeremy Martin said the town is getting calls about cutting down trees in the shoreland zone that are infested. He said shoreland zoning does not allow the trees to be cut down, but they can be pruned.

Schmeelk said an oak can withstand several years of defoliation, and still come back. If a tree was completely defoliated one year, he said to wait to see if the leaves come out again this year.

Patrick McCafferty, a Camden resident, School Board member and a masonry contractor, is testing a way to shoots pellets from a drone at the winter webs at high velocity, blasting the webs and exposing the small caterpillars to moisture. He said the idea "is purely conceptual at the moment," but also that he had interest building the drone from a company that has built similar projects before and from the University of Maine Extension.

He said at a recent worksite, he used a drone that can take high definition photographs to investigate the condition of various chimneys, then asked the homeowner for permission to document the Browntail moth webs on the property's massive oak trees, using the drone photographs and GPS coordinates. He then passed this information on to an arborist, who then worked on pruning the nests out of the trees.

McCafferty has talked to 12 to 15 town managers in southern Maine about what towns can do. He believes the immediate solution is to for individuals and associations to pool funding to hire arborists to mechanically prune concentrated areas and do insecticide injections. He said this is not something a town can do. It involves a lot of money, and does not involve town property, he said.

McCafferty referred to Shane Hendricks of Treeworks Landscape and Arboriculture, who was also in the audience, as working with the Megunticook Lake Association to mechanically prune Browntail moth webs from trees. Hendricks said has specialized equipment that can reach higher than bucket trucks. Hendricks offered to assist the town with infestation hot spots on town properties, such as Barrett's Cove on the lake.