HARPSWELL—Lobstering is big business in this island community. More than 200 residents depend on it for their livelihood.

So when the town started talking a few weeks ago about spraying the area with Dimilin, a chemical designed to kill browntail moth caterpillars, lobstermen got agitated.

"It's scary when the label says it is harmful to marine life," said David Wessel, a South Harpswell lobster man who started out in the business 20 years ago. "I'm opposed to spraying because of the big question mark. What can this stuff do to marine life? I wish there was another alternative."

Wessel's concerns are at the heart of a controversy to be resolved at Saturday's annual town meeting, when residents debate spending $45,000 to conduct an aerial spraying program to eradicate the browntail moth. Polls will open at 9 a.m., with the business meeting scheduled for noon at the Harpswell Island School.

The Maine Forest Service says more than 1,600 acres in Harpswell will need to be sprayed. Spraying may only occur 150 feet from the shoreline.

Dimilin has proven to be detrimental to shrimp, crab and lobster. But, unless towns spray, browntail moths can cause a public health hazard. The caterpillars' toxic hairs cause a poison ivy-like rash on the skin and in some cases, respiratory problems.

"The lobstermen are going crazy over Dimilin. They're concerned that the chemical is going to kill the lobster," said David Chipman, chairman of the Board of Selectmen.

Diane Cowan, a biologist and senior scientist for the Lobster Conservancy in Friendship, shares the lobstermen's concerns. Cowan is a former Harpswell resident, having served on its Conservation Commission and Marine Resources Committee. She says the long-term effects of Dimilin on the environment need to be studied.

"My recommendation is that Harpswell residents understand what they're doing. Learn the risks. Otherwise, this could turn out to be an experiment on nature," Cowan said.

Another controversial issue is a proposal to contribute $74,500 to the Curtis Memorial Library in Brunswick. Each year, Harpswell, which owns two small village libraries, shares the cost of operating the full-service Curtis Memorial Library.

This year, the library requested nearly 15 percent more money than last year, according to Budget Advisory Committee Chairman Alan Shaver. Committee members instead recommended contributing $66,850 toward the library, a 3 percent increase.

Harpswell residents also will finally get to see the results of years of negotiations with the Navy for the abandoned fuel depot on Middle Bay.

Last fall, the Navy transferred the 98-acre parcel to the town. Residents will be asked this year to spend about $66,000 to create more public access opportunities at the waterfront site. Money would be put toward boat ramp repairs, building repairs, picnic tables and portable toilets. Eventually, the site could be developed for light industrial uses.

Residents also will be asked to borrow $259,000 to purchase 77 acres on Doughty Point. The land, which is adjacent to the town office complex on Mountain Road, could be used for low-income housing or preserved as open space, Chipman said.