It’s against the law to harm the historic palms that line Royal Palm Drive in Wahiawa, as they are protected by the city’s Exceptional Tree Program.

Nobody told the invasive coconut rhinoceros beetles.

In the past month or so, area residents have started to observe the presence of the destructive beetles amid the trees that line both sides of the road from Glen Avenue to Uuku Street.

The royal palms are believed to be anywhere from 50 to 120 years old, planted for the drive leading to the home of the head of the pineapple packing company that would turn into the Del Monte Corp.

“The sad thing is they are such a historical landmark,” said Royal Palm Drive resident Micah Benavitz, who is president of the Wahiawa Community Business Association. “They are the signature tree of Wahiawa.”

The state Department of Agriculture and the state Department of Land and Natural Resources this week put up seven traps on the street in an effort to learn the extent of the localized infestation.

Coming up with a plan to protect the trees will be more difficult, but hopefully will follow, they said. The plan might include treating the infected trees with a special formula of insecticide.

Wahiawa is the latest area coping with the coconut rhinoceros beetle, which feeds on emerging palm fronds, often causing enough damage to kill a tree.

Since their initial detection at Joint Base Pearl Harbor-Hickam in December 2013, the beetle has spread across the island. And new discoveries of the 2-inch-long, black beetle with the signature rhino horn have only increased.

High-catch areas include the Pearl City Peninsula, Waipio Peninsula, West Loch, Ewa Beach and Central Oahu, while there have been increased detections on the North Shore and finds in Laie, Kahuku and Waimanalo.

Despite a decade-long, multi­agency battle against the bug on Oahu, eradication appears to be unattainable here, officials declared earlier this year. The war, they said, had turned to a containment and control strategy that aims to prevent the beetle from reaching the neighbor islands.

But even that’s been rough going. The beetles were detected near Lihue Airport on Kauai in late May. Since then, at least 34 beetles have been found in traps around Lihue, plus three larvae in Kilauea and 23 larvae at Nukolii Beach Park.

Another beetle, this one dead, was found among compost bags at a Maui big-box store last month.

In Wahiawa, Benavitz said he called several state and city offices regarding the Royal Palm Drive infestation but didn’t get the kind of help such historic trees deserved. Not until he contacted the media and got some coverage did the ball get rolling.

State Sen. Donovan Dela Cruz, whose district includes Wahiawa, contacted the state Department of Agriculture and DLNR, and an inspection and placement of traps soon followed.

Dela Cruz’s office issued a news release that quoted the senator: “The initial response from the HDOA Director lacked the urgency that I felt was necessary to save the historic palms.”

Contacted by the Honolulu Star-Advertiser, HDOA Director Sharon Hurd said she and a number of people on her staff were attending a cattlemen’s conference on Hawaii island on the weekend, and she wasn’t aware Dela Cruz tried to contact her.

But she was in contact with her new deputy director, Dexter Kishida, who walked Royal Palm Drive on Saturday and kept her informed, she said.

Hurd said officials have to come up with a treatment plan that won’t hurt the palms. That plan, she said, may include the use of the same pesticide that officials are having success with at Wailua Municipal Golf Course on Kauai.

Drones are being used to treat the crowns of the course’s 60- to 90-foot-tall coconut trees with the pesticide, Cypermethrin, also known as Demon Max. Hurd said the targeted use of the pesticide has been found to be effective in killing the beetles.

Benavitz said a town hall meeting is likely to be held regarding any treatment. Hopefully it won’t come too late, he said.

The beetles are active at night and are capable of flying from tree to tree over long distances, feeding on palms and other tropical crops using their front legs and horn to dig into tree crowns and feed on the juices in the inner spear.

If the beetles alone don’t kill the palms, the fungal or bacterial pathogens that follow might. According to agriculture officials, tree mortality after a coconut rhinoceros beetle attack is anywhere from 10% to 50%, with dead trees becoming a safety hazard as they threaten to fall unexpectedly after their trunks rot.

Residents who observe a coconut rhinoceros beetle are asked to immediately file a report with the CRB Response Team at 808-679-5244, email info@crbhawaii.org or call the state’s toll-free Pest Hotline at 808-643-PEST (7378). Reports should include your name, location and time the beetle was observed.