Big Island ranches are reeling as tiny invasive bugs wreak havoc on pastures

HONOLULU (HawaiiNewsNow) - A silent assassin is sweeping through pastures on Hawaii island, leaving a swath of destruction in its wake.

The invasive two-lined spittlebug was first spotted in Kona in 2016. Since then, it has done a tremendous amount of damage.

“It is completely decimating our mid to high-elevation pastures in Kona,” said Carolyn Wong, a grazing land management specialist with the USDA Natural Resources Conservation Service.

“This is evidence of kikuyu grass that’s died from spittlebug. You can see the leaves are still intact, but it’s all dead and brittle. You try and pull on it, it’s just all dead,” she said, pointing out an affected section of pasture.

Ranchers have watched the invasive insect ravage large areas on Hawaii Island’s west side — and summer is the spittlebug’s peak season.

Agriculture experts suspect the tiny insect piggybacked on imported plants that came from the southeastern part of the US.

It sucks nutrients and fluids from grass cattle graze on. What’s left is ground cover that’s weak, brittle, dead or dying.

“Kikuyu grass is one of the most important forage grasses that we have in the state. It supports probably around 70% of the livestock in the state. It’s highly susceptible to two-lined spittlebug,” said Mark Thorne, a range and livestock specialist with the University of Hawaii College of Tropical Agriculture.

The spittlebug population is growing at an alarming rate. The insects have infiltrated more than 176,000 acres of ranch and pasture land.

When grazing grass disappears, the pasture’s ecosystem is thrown into chaos.

“We’ve got carpet grass that’s taken it’s place. We have lots of fire weed which is toxic to cattle,” Wong said. “We start to see the whole plant community completely shift from a grass dominated, healthy, productive landscape to something completely dominated by weeds.”

Some Kona ranchers have been forced to reduce the size of their herds because there isn’t enough grass for cattle, and it’s very expensive to buy feed.

“The fear right now is it could easily spread to other areas on the Big Island, and for that matter statewide,” said south Kona rancher, Keith Unger.

Experts acknowledge the spittlebug will be impossible to eradicate. They’re focusing on managing its spread and controlling its impact.

“We’ve been able to identify those grasses that are very sensitive to spittlebug attack, and some of those grasses that are more resistant. We’ve found that there’s an indigenous fungus in Hawaii that affects the spittlebugs,” Thorne said.

The state appropriated $350,000 to help affected ranches recover, and other ranches to prepare for the insect’s arrival.

“We’ll have a better chance of avoiding as severe of a disaster, hopefully, in Waimea, Kohala, all the other areas that are vulnerable right now to two-lined spittlebug,” Wong said.

She believes a key weapon could be the state’s full implementation of its bio-security plan.

“The biggest concern that we have is that the spread will happen artificially, that it will be transported into those zones,” Thorne said.

A female spittlebug can lay 50 to 200 eggs in her lifetime. Areas can quickly be overrun by a swarm.

“Cattle can survive on this, but this land’s productive potential has taken a really really big hit,” Wong said.

Until an effective practice is found to slow their spread, spittlebugs will continue eating their way through Kona’s grasslands and moving on to greener pastures.

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