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Lauhala weavers should be on the lookout for invasive beetle

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David Eickhoff
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An invasive beetle that feeds primarily on coconut trees has recently been found in another one of Hawaiʻi’s famous native plants – the hala tree. The coconut rhinoceros beetle is damaging local hala trees, and that worries cultural practitioners whose traditions depend on a healthy supply of hala.

Kahakuloa native Pohaku Kahoʻohanohano has been weaving the leaves of the hala tree for 29 years. He can weave the long, sharp and spiny leaves into mats, hats, bracelets, and more. He was shocked to hear the ancient Hawaiian plant is now being threatened by an invasive beetle.

“I definitely don’t like to hear that,” says Kahoʻohanohano. “It’s devastating for weavers and lei makers and anyone who uses the hala for any reason either for medicine, for fibers, for lei.”

 The invasive beetle bores into the soft tissue of the hala tree as seen here
The invasive beetle bores into the soft tissue of the hala tree as seen here.

The coconut rhinoceros beetle known by its acronym CRB was first detected on Oʻahu in 2013. Darcy Oishi, acting manager of the Plant Pest Control Branch at the state Department of Agriculture, says attacks on native plants such as hala are rare.

“This is what happens when infestations get really high,” says Oishi. “The first report of this in hala was back in 2018 over in Waiʻawa. We’ve only had four cases of this since, but this is an indicator that the beetle populations are getting high, much higher than I would like.”

He says Waiʻawa is the biggest CRB hot zone and Iroquois Point is another. Agricultural land between Mililani and Kunia is turning into hot zones. These black beetles average two inches in length with a visible horn and can be found primarily feeding on varieties of palm trees.

 Coconut rhinoceros beetles are black beetles averaging two inches in length with a distinguished horn.
CRB Response
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Coconut rhinoceros beetles are black beetles averaging two inches in length with a distinguished horn.

“It’s really looking for soft tissue to feed on,” says Oishi. “So the adult beetle will go to the crown of a coconut, portions of the hala, to feed and get the juices that it needs, which basically helps it get through the next important stage of its life, which is the mating and reproduction aspects. ”

Oishi says the agency’s response has been to focus on CRB population control, employing methods such as systemic pesticides and composting or burning of potentially infested material.

They’re also looking at the potential use of drones to apply pesticides to the tops of palm trees. Oishi says the success of the agency’s efforts is highly dependent on public awareness of the fast-spreading beetle.

As for Kahoʻohanohano, he says this news comes as lauhala weavers statewide continue to grapple with the invasive hala scale, which renders the leaves useless to weavers. He hopes new groves of clean hala can be planted to ensure this important native plant is protected.

“If we have no hala trees, we obviously have no material, “ says Kahoʻohanohano. “We need these plants for survival.”

For more information on the coconut rhinoceros beetle or to report CRB damage, visit crbhawaii.org/.

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