While those bugs are expected to be sent here soon for laboratory testing, scientists in Brazil are zeroing in on identifying more fungi that might further undermine the spread of the aggressive invader.

"For the long-term, biological control is the answer," said Lloyd Loope, research scientist with the U.S. Biological Resources Division's Haleakala Field Station.

The miconia tree, with its attractive purple and green foliage, was introduced to Hawai'i as a garden-shop ornamental in the 1960s. Alarm bells weren't set off, however, until 1990, when scientists found the plant growing wild in East Maui and also learned it was taking over vast sections of forest in Tahiti.

Scientists would soon find miconia up and down the Hawaiian chain, from a few trees here and there on Kaua'i and O'ahu to entire hillsides on Maui and the Big Island, home of the largest infestations.

Scientists feared the plant, free of the fungi and insects that keep it in check in its native Latin American habitat, would transform the Hawaiian landscape, its large leaves shading out native rain forest species and killing the plants underneath its canopy. The result would be single-species ecosystems and crippled watersheds.

Eradication campaigns were launched and millions of dollars in public money has been expended in the miconia war.

While the outlook for eradication appeared bleak just a few years ago, officials now say they've gained the upper hand in many areas of the state, including on Maui, where an influx of money from the National Park Service has helped to ramp up control efforts.

"I've been amazed at what has been accomplished in the last couple of years," said Mindy Wilkinson, the state's invasive species coordinator.

Today, there are no mature miconia trees known to exist on either O'ahu or Kaua'i, Wilkinson said. That's not to say there isn't more work to be done. Each tree can produce thousands of seeds that can survive for five years or more in the ground, so miconia isn't going away just yet, she said.

On Maui, the National Park Service is contributing $500,000 to the control effort, a doubling of the annual budget. A strategy of destroying the fruiting trees with both aerial herbicide spraying and ground teams has resulted in reducing the density of the main East Maui infestation and has kept it from expanding, officials said.

"Maui has done a phenomenal effort," Wilkinson said.

The Big Island, meanwhile, has the biggest infestation, more than 20,000 acres, and officials are re-evaluating their control strategy in light of logistical and budget limitations.

To date, the Big Island Invasive Species Committee has focused on working the perimeter of the infestation, much like fighting along the edge of a brush fire to make sure the flames don't spread. But the area is vast and miconia growth is exponential, and officials are now considering redeploying their troops to ensure protection of the island's natural preserves, including Hawai'i Volcanoes National Park and Hakalau Forest National Wildlife Refuge.

While control work is buying time, biological control appears to be the best hope for an ultimate victory.

A fungus from Brazil that was released in 1996 is now starting to show signs of working in the wettest areas of the state, where it is defoliating some plants and likely undercutting reproduction, officials said.

Meanwhile, university scientists in Brazil, under contract with the state, are working to find other fungi that will attack miconia. Former University of Hawai'i Professor Clifford Smith has been herding that project along.

In Costa Rica, surveys of the natural miconia populations have led to discovery of at least a dozen insect species with potential for biological control. So far, scientists at the University of Costa Rica have studied two species in detail: a butterfly whose larvae eat miconia leaves, and a small, reddish, aphid-like psyllid that primarily infests shoot tips and stunts plant growth. A weevil that feeds in the plant stems also looks promising.

But there's still at least a couple of years of laboratory testing before they can be unleashed on Hawai'i's miconia. Scientists must prove the bugs will attack miconia — and miconia only — and do it well before the government will authorize any release.

Tracy Johnson, research entomologist with the U.S. Forest Service in Hilo, said he's optimistic the insects and the fungi can do the job, probably working in concert with one another to attack different parts of the plant.

"It's a big challenge," said Johnson, who is working through red tape to get the first couple of candidate insects imported to Hawai'i. "Controlling a tree that produces so many seeds and can spread so easily — that is a big challenge."

Julie S. Denslow, research ecologist with the U.S. Forest Service, said biological control does offer hope, but "it's not the silver bullet."

It will not eradicate miconia by itself, she said. Rather, it will reduce the plants' vigor and slow its spread, allowing for much easier control by conventional means.

Biological control represents only a small portion of the miconia control budget — a couple of hundred thousand dollars — but it may be the most important at this point, said Loope on Maui.

"Miconia is such a huge threat," he said, adding that keeping it under control is essential. "The alternative is giving up on biodiversity in the rain forest."