Wasp could take sting out of caterpillar

By MELISSA TANJI Staff Writer
The state hopes it can use a parasitic wasp to control the invasive nettle caterpillar, which packs a punch with its stings comparable to those inflicted by jellyfish.

Lissa Fox, public relations and education specialist with the Maui Invasive Species Committee, said the “cute” but harmful and sometimes painful nettle caterpillar has caused problems and stung people in Haiku nurseries and yards.

A sting from a nettle caterpillar may include itching, welts and blisters. In more serious cases in which people have difficulty breathing, a bite can lead to a doctor’s visit or a trip to the hospital emergency room.

The critter, which grows to as much as an inch long, has an appetite for a wide range of plants. It has a dark stripe down its back and is covered with light-colored venomous spines and hairs.

While contact with the nettle has been confirmed in Haiku, Fox said she has heard reports of the insect being spotted in Kihei.

Fox said her group has loaned a nursery in Haiku a sprayer to chemically control the nettle caterpillar. While there has been some success, the chemicals have not completely eradicated the caterpillars.

The caterpillars are as hard to control as cockroaches in one’s home, she said, adding that the pest could spread quickly to the rest of Maui.

The nettle caterpillar, or Darna pallivitta, is also already established on Oahu and the Big Island and is thought to have been spread by infested nursery plants from the Big Island.

It was first found in 2001 at a plant nursery in Panaewa on the east side of the Big Island. It is believed to have arrived in Hawaii on Rhapis palm seedlings imported from Taiwan.

The state is hoping to release the parasitic wasp, Aroplectrus dimerus Lin, to seek out the nettle caterpillar larvae, attack and kill it.

According to a draft environmental assessment on the biocontrol project last November, the state said the parasitic wasp specifically seeks out the nettle caterpillar.

After it stalks its prey, the female wasp stings and immobilizes the nettle caterpillar larvae and then lays eggs on them. The state says only the nettle caterpillar would be affected by the wasp.

State officials worry the tourism industry could be hurt if the caterpillar were to become well-established in landscaped areas at hotels and along beaches.

Neil Reimer, manager of the Plant Pest Control Branch of the state Department of Agriculture, said a final environmental assessment should be completed for the project within a month.

He said he hopes to have all of the approvals and permits to release the wasp by the end of the summer as there is a “serious” problem of nettle caterpillars on the Big Island.

Reports of people getting stung by nettle caterpillars increase during the summer months when the pest’s population increases, according to the state.



• Melissa Tanji can be reached at mtanji@mauinews.com.