Visitors flock to the Hawaiian Islands for sun-soaked holidays filled with silky beaches, turquoise water, lush green hillsides — and naked palm trees missing their leafy crowns?
That possibility has state officials worried because Hawaii’s iconic swaying palm trees are under attack. Their nemesis is the latest in a long line of invasive species to arrive here: the coconut rhinoceros beetle.
Much as the Asian long-horned beetle attacked maple and elm trees on the East Coast, the coconut rhinoceros beetle could devastate Hawaii’s palm trees and move on to bananas, papayas, sugar cane and other crops afterward. Adult beetles burrow into the crowns of palm trees to feed on their sap, damaging developing leaves and eventually killing the trees.
Concerns that the thumb-sized pest, named for its curved horn, could hitch a ride to California or Florida and attack thriving palm oil and date industries there have prompted federal and state officials to declare the beetle’s discovery in Honolulu a pest emergency.
One year into the fight — Dec. 23, 2014, was the anniversary of the beetle’s discovery on coconut palms at Joint Base Pearl Harbor-Hickam — state officials are cautiously optimistic.
“At this point, eradication is still possible. It’s going to take a long time, but it’s still possible,” said Rob Curtiss, incident commander for Hawaii’s coconut rhinoceros beetle eradication program, a joint operation of the U.S. and Hawaii departments of agriculture.
The urgency to address the problem is both cultural and financial. The coconut tree is depicted in the ancient hula, and in some neighborhoods, every other house has a palm tree growing in the front yard.
“If somebody is coming to buy a property in Hawaii, they will expect nice palm trees,” says Curtiss, an entomologist with the plant pest control branch of Hawaii’s Department of Agriculture.
Curtiss leads a group of about 40 people charged with eradicating the bug. Field teams check trees, set up traps and monitor mulch piles for signs of beetle larvae. So far, they’ve put up 2,700 beetle traps across Oahu and surveyed more than 100,000 trees.
On a recent Friday, team leaders Chad Goldstein and Zachary Potter headed out on their daily rounds to Iroquois Point, just across the harbor from beetle ground zero at Pearl Harbor. The former military housing community is filled with coconut trees.
The pair scanned the tree tops for leaves that have been snipped in an inverted V-shape — a sign of beetle damage. Most of the affected trees in this community have been tagged and are continually monitored. Less than 100 yards away, Potter spotted two more trees just starting to show damage.
“When we first started coming out here six months ago, none of the trees were damaged,” Potter said. “But now a lot of the coconut trees are just completely torn up. It’s really sad.”
It takes a practiced eye to spot early damage on an otherwise healthy tree, and the habit can be hard to break off duty.
“I’ll be at the beach and find myself staring at coconut trees all afternoon,” Potter said.
The pair continued on their rounds, checking their maps to find the traps, which resemble 4-foot-long black lanterns with a white plastic cup at the bottom. The nocturnal beetles are attracted to the trap by a pheromone lure and the glow of a small solar-powered LED light. When a beetle bumps into the trap, it falls into the cup and can’t escape.
The beetles are native to Southeast Asia and have spread throughout the Pacific. Pictures of beetle-ravaged groves in Guam show barren trunks jutting 40 feet out of the ground like giant twigs.
Studies of Palau in the 1950s showed that half of all palms on the island were killed within 10 years of introduction. A more recent survey in 2006 of infested areas in Malaysia showed that beetles wiped out 67% of palm crops.
Officials suspect the beetle came to Hawaii in air cargo.
Entomologists still haven’t developed an effective pesticide to kill the beetle and its Vienna sausage-sized larvae. Chemicals used successfully in Southeast Asia aren’t approved for use in the U.S. A virus and a fungus targeting the beetle are possible, but researchers still must conduct studies to make sure they won’t harm other native species.
Mapping the infestation is step one. So far, the beetle appears to be contained to three major areas, all on military property. Of the 1,500 beetles caught in 2014, only 60 were found off base. Most days, except on the military base, the traps are empty, bar the occasional live gecko.
Step two is destroying breeding sites. The bugs breed in mulch piles, which means a lot of mulch grinding and burning.
The bug doesn’t appear to have landed on the neighbor islands, but expanding monitoring operations there is on Curtiss’ agenda for 2015. Eradication efforts cost the state and federal governments $2.5 million in 2014. Curtiss has asked for more as the operation continues to ramp up this year.
He’s in the process of buying a drone with a camera to peer down into tree crowns — it’s cheaper than hiring a truck with a cherry picker. He’s also hoping to add scent dogs and dog handlers to his staff to help search for beetles in mangroves and other areas with thick brush.
Eradication efforts in Honolulu are helped along somewhat by white egrets and especially mongoose, the latter of which burrow into mulch piles to gobble larvae.
The beneficial role of the mongoose is welcome, though a surprise. It’s an invasive species in Hawaii as well, and has decimated many native bird populations.
Lin is a special correspondent.