WAILUKU, Maui — Despite doubts about whether the Erythrina gall wasp can be stopped, Maui's mayor has pledged up to $100,000 to help combat the spread of the insect that threatens the native wiliwili tree and its nonnative cousins, the coral tree and the tall wiliwili.

Maui conservation officials, led by research biologist Art Medeiros of the U.S. Biological Resources Division, met with Mayor Alan Arakawa on Friday and proposed a control strategy that includes tree trimming and mulching.

The Maui Invasive Species Committee is conducting islandwide surveys to help determine just how widespread the wasp infestation is and whether the control effort will ultimately be worth it, officials said.

Maui is home to Hawai'i's last intact native wiliwili forest, part of a 256-acre fenced preserve on the leeward side of Haleakala. It has been estimated that the lower southern flank of the mountain has between 10,000 and 20,000 native wiliwili.

The county money would come from a fiscal 2006 budget fund earmarked for emergency alien species control. The Maui County Council might even be asked to add more money, officials said, but that hasn't been decided yet.

"We are faced with a real nasty situation," said Rob Parsons, Maui County's environmental coordinator.

First detected on O'ahu in April, the gall wasp spread rapidly across that island and was recently discovered on Kaua'i, the Big Island and Maui. It is believed to have gotten to Hawai'i in cargo from Taiwan.

Ken Teramoto, chief of biological control at the state Department of Agriculture, said last week that any control effort likely would be a waste of time and resources, considering how fast it is spreading.

Parsons agreed that it may be too late to stop it, but said that "if it's early enough, we may have time to contain it."

Surveys in the past few days have found that the wasp has spread beyond Kahului to Pa'ia, Ma'alaea and a few other places. A light infestation was found at Star Market in Kihei, but most other locales in South Maui appear to be pest-free.

On Saturday, a work crew demonstrated the proposed control strategy at Maui Community College in Kahului, where trees of the genus Erythrina have been hit hard. In the control effort, three large coral trees were completely trimmed and four partially trimmed, with the cut material chipped and spread on the MCC soccer field and covered with black plastic, allowing the heat to kill any remaining larvae. Two hedgerows on MCC property also were cut down to about 2 feet above the ground.

Parsons said crews probably will be asking private landowners for permission to trim their Erythrina trees.