Coconut rhinoceros beetle grubs have been found at a home in Waikoloa Village, state Department of Agriculture officials said Friday.
It’s the first discovery of the invasive beetle on the Big Island.
“It will kill palm trees,” said Franny Kinslow Brewer, manager of the Big Island Invasive Species Committee. “It will also attack other things, like bananas — a lot of things that are related trees. Basically, the adults will bore into the bottom of the fronds, and then, they’re eating the tissue inside. Then they lay their eggs.”
Tree mortality after the beetles attack has been reported to be anywhere from 10% to 50%. Dead trees then become a safety hazard as they may fall unexpectedly after the trunk rots, potentially resulting in bodily injury or property damage.
On Oct. 11, the Waikoloa resident found five large grubs, or larvae, in a decaying palm tree stump on the property and reported it to the Coconut Rhinoceros Beetle Response Project.
DOA staff responded to the site and collected the specimens. A University of Hawaii laboratory in Honolulu identified the grubs as CRB, using a DNA-based test.
On Wednesday, the resident reported finding one more grub on the property. No other grubs or adult CRB have been detected so far on Hawaii Island
“We need heavy, heavy-duty vigilance from the community. We need people reporting any time they see something suspicious,” Brewer said. “This insect is not established yet on the Big Island. It is not widespread. It’s in one limited location.”
DOA crews on the Big Island and CRB response staff from Oahu surveyed the immediate area and didn’t find additional CRB damage. A multiagency team will continue to survey the area. Additional pheromone traps, used for early detection of infestations, are being deployed from Waikoloa Beach to Waimea, as well as other areas around the island.
Surveillance for CRB has been ongoing on all islands, including traps at airports, harbors and other strategic locations. DOA staff also are trying to trace the origin and the pathway of the grubs found in Waikoloa.
“We’ve been doing surveillance for five years now. We have never detected one before,” Brewer said. “We do palm surveys annually. We have never seen palm damage before. So, we have no reason to think this is something that’s widespread and established. At this point, it’s possible that we can contain this, and we can eradicate it. But we can only do that if we get very early information from our community. That’s how this detection happened.”
Brewer said people are more likely to find the grubs rather than adult beetles.
“On Oahu, they’re finding them in any kind of coconut debris,” she said. “So, if you have a pile of coconut fronds that are green waste, that are decomposing in your back yard — that’s where they love to lay their eggs. That’s where they love to develop their larvae. If you have a stump of a coconut pond in the back yard, they love that.”
She said the beetles also have been found on Oahu in mulch, compost and even potting soil, and residents are being asked to be vigilant when purchasing these materials and to inspect bags for evidence of entry holes. Adult beetles are about 2 inches long, all black and have a single horn on their head.
“If people here are buying bagged compost or mulch or potting soil, what we need them to do is to open the bags, spread (the contents) out, and immediately look for anything that looks like a larva or beetle,” Brewer said. “So, if you aren’t ready to use it yet, just don’t put the bag behind the garage and let it sit for three months. Put it in a wheelbarrow, get yourself a large Rubbermaid container, and just sort of sift through it. Make sure there’s nothing in it before you use it.”
The CRB, a large scarab beetle, was first detected on Oahu in 2013. It has since been found in many Oahu neighborhoods, and was detected in May on Kauai, where eradication efforts continue.
Last week, several agencies were involved in the pesticide treatment of palm trees via drones at a Kauai golf course. More than 90 palm trees were treated, and 40 adult CRBs were killed, according to the DOA.
“We’ve been anticipating this,” Brewer said. “We were hoping the Waikoloa larvae tests weren’t going to come back as CRB. After the Kauai detection, we started doing some prep, so we’re training a sniffer dog, Manu, here on the island.
“We are asking residents to be vigilant. It’s not established. It doesn’t have to become established.”
Residents are encouraged to go to the CRB Response website at https://www.crbhawaii.org/ to learn more about how to detect the signs of CRB damage, how to identify CRB life stages, and how to report any suspected signs of damage or beetles/grubs via the CRB reporting feature.
Reports of possible CRB infestation may also be addressed to the CRB Response team at (808) 679-5244, email info@crbhawaii.org or by calling the state’s toll-free Pest Hotline at (808) 643-PEST (7378).