Tom Greenwell said he initially thought the damage to his coffee beans came from termites.

But he later realized an alien pest was drilling into the beans.

"The beans don’t roast well when they get holes in them," said Greenwell, president of Greenwell Farms LLC on the Big Island. "It looks like a rotten tooth. They’re unusable. I have not really seen this kind of damage on a bean."

As Big Island coffee farmers harvest their berries from trees, they are finding a new foreign beetle — the coffee berry borer — that at best threatens their bottom line.

An estimated 600 to 700 coffee farms occupy a 22-mile stretch along the rocky, volcanic slopes of Kona, where dry winters and wet summers contribute to producing a premium coffee bean.

The coffee berry borer, Hypothenemus hampei, is native to Central Africa and found in scores of coffee-producing countries, including South America.

But it was not discovered on the Big Island until September by a University of Hawaii student.

State agricultural officials said that if its spread is not halted, the pest could blight Hawaii’s coffee industry, with farm revenues exceeding $27 million in 2009-2010.

State and federal agricultural officials are conducting an investigation into how the coffee berry borer entered Hawaii and possible ways to control its spread.

A state Department of Agriculture survey of 100 farm sites statewide found the beetle only on the Big Island.

Department officials are looking at using a fungal spray that has been somewhat effective in other countries.

"It’s not a silver bullet," said Neil Reimer, the department’s Plant Pest Control Branch manager. "It’s just another tool for the grower."

The Kona Coffee Farmers Association has called for the immediate suspension of green coffee imports to Hawaii. Coffee processors import husked green coffee beans and roast them to blend into Kona coffee.

Association President Bruce Corker said his group feels the lack of adequate controls allowed beetles to enter through the importation of green coffee beans.

Reimer said last week the importation of green coffee is probably not the point of entry, because beans are fumigated. He said the other possible means of entry include Internet mail orders and the smuggling of coffee seeds or tree cuttings.

Agricultural officials said they do not have an estimate of the damage caused by the beetle so far.

Based on the extent of the infestation, Reimer said, the beetle has been on the Big Island for a few years.

Greenwell, whose business also processes coffee from other farmers, said one coffee producer found damage as high as 25 percent.

"It’s way beyond the profit margin," he said.

He said about 10 out of 100 farms had 10 percent of their beans damaged by the borer.

In one approach, farmers and agricultural officials are looking for ways to decontaminate coffee bags and trucks.

They’re also planning to remove all the berries from trees and set traps during tree-pruning season in a couple of months.

"We’ve got it," said Greenwell. "And now we need to buckle down as fast as we can to minimize the spread of this to other farms that don’t have it."