A court hearing opened Friday over an attempt to temporarily block state, federal and private conservation officials from releasing millions of mosquitoes into the wilds of Maui.

The project aims to save rapidly diminishing native Hawaiian honeycreeper forest birds from extinction, but a Maui-based group called Hawaii Unites says the effort is an experiment that could go wrong and needs more study.

Hawaii Unites and founder Tina Lia of Maui filed a motion for a temporary restraining order and preliminary injunction against the state Board of Land and Natural Resources and the Department of Land of Natural Resources.

The plaintiffs are asking the court to order the state not to release incompatible male mosquitoes and any lab-reared Wol­bachia bacteria-infected mosquitoes in rural areas of East Maui, including state land and Haleakala National Park.

The state and a multi-agency partnership called Birds, Not Mosquitoes have proposed using an “incompatible insect technique” to control mosquito populations that transmit avian malaria, the disease largely blamed for putting three species of Hawaiian honeycreeper on the brink of extinction.

The plaintiffs earlier filed suit demanding an environmental impact statement rather than the less rigorous environmental assessment. But after they learned that pilot releases had already begun, they filed for the restraining order and injunction.

Officials acknowledged Friday that a few thousand incompatible male mosquitoes have been released into the wild in remote parts of Maui. The pilot releases so far have been a success, they said, and the project should be ramping up in a couple of months.

The proposed action, outlined in environmental documents, consists of repeatedly releasing incompatible male mosquitoes that reduce the reproductive potential of wild mosquitoes.

Under the proposal, only laboratory-raised male mosquitoes, which do not bite birds or people and therefore do not transmit diseases, would be released. The males would mate with wild female mosquitoes, whose eggs would not hatch.

When conducted repeatedly over time, releases of incompatible mosquitoes are expected to suppress the wild mosquito population by as much as 90%, according to the plan.

On Friday, Circuit Judge John Tonaki heard nearly six hours of testimony, including from Lia and disease vector expert Dr. Lorrin Pang, the Maui District health officer.

Pang, who has lots of experience studying tropical diseases, told the court he doesn’t think the project and its potential for side impacts have been studied enough to go forward at this time.

“If it works as planned, it’s wonderful,” he said. “But I wonder if it’s as effective as they think it will be and if they’re not over-promising on the side effects if things go wrong.”

Pang pointed to a study that suggests that the Wolbachia bacteria could spread horizontally to other species — and much faster than on the evolutionary timescale that project planners told him was the level of risk.

He said another study warns of the potential for the bacteria to boost the chances of West Nile Virus taking hold in the islands.

The project’s environmental assessment doesn’t address enough scenarios or look at alternatives, he said, and it does not contain mathematical models to reliably predict outcomes.

Lia told the court the environmental assessment is misleading, deceptive and leaves out key details. She described the project as experimental because it uses a type of mosquito never used before.

“The information was misrepresented to the public,” she said, “and I will put it nicely as misrepresented to the public.”

Lia, a bookkeeper and nonprofit volunteer from Kihei, said that while project officials say Wolbachia is already found in Hawaii, other documents described it as a different, or foreign, type of Wolbachia, sourced from Kuala Lumpur, Malaysia.

What’s more, the environmental assessment doesn’t even mention the rate of accidental female releases, which Lia discovered in her research as being 1 in 250,000 mosquitoes, according to an Environmental Protection Agency figure. That means more than 3,000 females could be released per week over the next 20 years, she said.

Lia said that is concerning to her because “females bite and breed and spread disease, and because it was misrepresented to the public that only males would be released.”

She said her formal comments about the document were not seriously considered by project planners.

“I felt that the public participation process was not being honored,” she said. “I felt very much like the decision to do this project had been pre-decided, and they were working the documents around a decision that had already had been made.”

Entomologist Nicole Ferguson, a Maui Forest Bird Recovery Project field supervisor, testified for the state and disputed some of the claims made by previous witnesses.

Among other things, she said the targeted strain of Wolbachia has been in Hawaii for more than 100 years, and there is no known transmission of the bacteria to other species. She also said the rate of accidental female mosquito release is 1 in 50 million, and even if more infected females were accidentally released, the result would not be catastrophic. She said it would only mean the method would be less effective over time.

During a break Friday, state Division of Forestry and Wildlife Administrator David Smith said he understands people have concerns, and the state wants to address them.

“But we literally have birds going extinct, and we don’t want to see any delay,” he said.

Last week the department announced that the akikiki on Kauai is now down to an alarming five individuals. Smith said the other honeycreepers will soon be critically endangered.

The hearing will start up again Aug. 15.