With Hawaii coffee farms under attack by a wave of alien pest species, crop yields are off by as much as 50% this year. But farmers may soon be getting some help in the form of a tiny bio-control agent.

Agricultural officials are proposing the widespread release of a parasitic wasp species, originally from Africa, to suppress infestations of the coffee berry borer beetle across the state.

Public comment is being sought on a draft environmental assessment written by the University of Hawaii College of Tropical Agriculture and Human Resources in collaboration with the U.S. Department of Agriculture and the state Department of Agriculture.

The 30-day comment period ends Jan. 9.

Phymastichus coffea is a small parasitic wasp whose larvae feed on adult coffee berry borer beetles in the native range in Africa, causing beetle death before it can penetrate the coffee berry and lay eggs.

According to the draft document, parasitic wasps have been used around the world to fight the coffee berry borer, considered the most devastating coffee pest in the world.

The small beetles bore into coffee cherries, where they lay their eggs. Larvae then feed on the bean, which hurts coffee quality and yield.

Hawaii agricultural officials imported the wasp species to the USDA quarantine containment facility in Volcano, where they put it through a range of tests to determine whether it might attack nontarget species and therefore pose a risk to the environment.

The testing, they said, demonstrated that P. coffea is host specific to the Hypothenemus species — none of which are native to Hawaii — and does not attack any native beetles in the same family as the coffee berry borer or any other beneficial beetles tested.

Scientists have concluded that the wasp is unlikely to cause any harm to Hawaii’s environment. The tiny insect is said to be half the size of a sesame seed and does not sting people.

In the islands, the coffee berry borer was first discovered on the Big Island in 2010. Since then it landed on Oahu in 2014, Maui in 2016 and Kauai in 2020.

Between 2011 and 2013 alone, damage from the insect cost the state more than $25.7 million in coffee sales, officials said.

Since 2020, coffee farmers have had to deal not only with the coffee berry borer but coffee leaf rust, a fungus considered an even greater threat to the $55 million Hawaii coffee industry.

Suzanne Shriner, president of the Kona Coffee Farmers Association, said most farmers are hoping the tiny wasp will help battle the coffee berry borer and cut down on the amount of pesticides they have to use.

Coffee yields were cut in half this year, she said, largely due to dry summer conditions that allowed the coffee rust fungus to help cripple the crop.

But it was also a bad year for the coffee berry borer, which ruined about 30% of the crop, Shriner said.

To deal with the pests, farmers are using a fungus spray to kill the coffee berry borer and a fungicide to attack the coffee rust.

“The problem is the two neutralize each other,” Shriner said, which is why most farmers will be welcoming the wasp.

Shriner, who helped write the draft DA’s cultural assessment, said that for coffee farmers, the wasp may end up being the difference between being profitable or not.

Shriner said she’s hoping that within a year the wasps will be released in select locations to see how they do.

“It’s been a hard year on the farm,” she said. “Most farmers think the wasp is the favorable option.”