The two-lined spittlebug has been a growing problem for ranchers on Hawaiʻi Island over the last couple years — and experts warn it’s also a threat for the whole community.
The insect was first discovered in Hawaiʻi in 2016, and covers around 300,000 acres of land in the south Kona area. It eats the same grasses — like kikuyu and pangola grass — that feed cattle, and since 2016 has cleared pasture land on the island.
It’s already cost local ranchers thousands of dollars.
“It is really devastating … not only devastating to ranches and their forage and their ability to raise cattle, but losing cover ground is really going to be negatively impacting runoff to the ocean,” said Nicole Galase, managing director for the Hawaii Cattlemen’s Council.
The TLSB is about the size of a fly and is mostly black in color, but it’s named after the two distinct orange or red bands that run across its body. It’s also part of a family of insects known for their leaping ability.
The spittlebug infesting Hawaiʻi is native to the southeast part of the U.S., and likely originated in Florida.
From about 2021 to 2023, it covered about 180,000 acres of land in Kona. The TLSB isn’t particularly drought-tolerant, so its ability to reproduce was suppressed during those dry conditions.
But Mark Thorne, a researcher at the University of Hawaiʻi’s College of Tropical Agriculture and Human Resilience, said it’s been allowed to expand south since then.
“The last two years have been really active. The Kona area has been really wet, which is pretty favorable climate conditions for the spittlebug, and so it has spread pretty rapidly,” Thorne said.
In large numbers, the TLSB can clear pasture land used to raise cattle. That affects how much beef ranchers can produce, and in turn hurts local agriculture. For some, the damage has been significant.
“The ranches that I've worked with have lost anywhere from 20% to 30% of their pasture area. Some of them have destocked by nearly 50%, which is pretty significant when you start thinking about the value of a cow today,” Thorne said.
Cutting a herd of 500 in half could mean a loss of $300,000, Thorne estimated.
And the spittlebug has done more than spread through the Kona area. Over the last year or so, it’s been found in two new areas on Hawaiʻi Island — at South Point and Glenwood.
It’s thought that spittlebug eggs were carried there by hitching rides on heavy equipment, such as bulldozers, that were transported from Kona.
It’s also an issue for more than just ranchers. The pest has also been known to attack residential areas, too. They usually start out as round dry patches of lawn.
“Anywhere where there's grass, even your lawns, it's going to be an issue,” Galase said.
The insect also hurts efforts to restore native flora. After the TLSB clears an area, invasive weeds, which aren’t great for the ground and cattle don’t eat, often take over.
What's being done to stop the TLSB?
Ranchers have been trying to manage the spittlebug through intensive grazing, growing resistant grasses and other methods, but there isn’t a surefire way to eradicate them.
The state has directed funding to research and manage the two-lined spittlebug. It’s one of a handful of pest species in the state with specific funding in the state budget that passed this year — about $600,000 this and next fiscal year to manage the pest.
Still, it’s generally been overlooked as an invasive species threat compared to others, like the coconut rhinoceros beetle and the little fire ant.
It should be getting more attention, Thorne said.
“It's out in the forest, it's in the people's lawns in Kona, and they're not seeing this and they’re not managing it. So you have populations that are just going rampant. It's a huge problem,” he said. “And it doesn't just belong to the ranchers — this belongs to everybody in the state. It's going to affect everybody in the state one way or the other, indirectly or directly.”
He said more funding and policies like quarantines used for other pest species should be implemented to keep the spittlebug from spreading even more. Thorne manages a website with more information on the two-lined spittlebug, and a link to a phone app to help positively identify and report it.
Hawaiʻi is part of a multi-state Rangelands Partnership, in which experts provide information to support healthy and sustainable rangelands.
The TLSB Hawaii group, made up of the Hawaii Cattlemen’s Council, UH and government agencies, is also asking the public to report the pest and help spread awareness. The group said members of the public can help stop its spread by cleaning their shoes and gear when leaving an infested area.
