Department of Agriculture

STINGING CATERPILLAR EXPANDING ITS RANGE ON THE BIG ISLAND

HONOLULU – Reports of stinging incidents from the nettle caterpillar are increasing on the east side of the Big Island as infestations of the caterpillar expand.  Residents in infested areas should be aware that the caterpillar may cause painful stings and may cause allergic reactions in those who are sensitive to the venom.

The nettle caterpillar (Darna pallivitta)  was first detected in September 2001 at an ornamental palm nursery in Panaewa near Hilo and has now spread to Waiakea, Waiakea Uka, Kaumana, Piihonua, Keaau, Kurtistown, Hawaiian Paradise Park and Orchidland.  Reports of stinging incidents are increasing as these caterpillars come into contact with more people. 

Nettle caterpillars have a dark stripe down its back and grow to about one-inch in length.  It also has light-colored venomous spines and hairs.

If stung, treatment recommendations include immediately washing the affected area with soap and water to remove any residue, applying ice to reduce swelling and consulting a physician to determine if further treatment is necessary.  Individuals who are sensitive to the venom should seek prompt medical attention, especially if they experience difficulty breathing or if they are stung in the eyes.

As nettle caterpillar populations are gradually dispersing as adult moths, residents in infested areas should consider wearing protective clothing, such as long pants and shirts, gloves, shoes and protective wear for the face and eyes while working in the yard.

For more information on the nettle caterpillar, click here

HDOA and the University of Hawaii College of Tropical Agriculture and Human Resources are jointly researching potential biological control agents – natural enemies of the nettle caterpillar that specifically attack this pest without harming native or other beneficial insects.  Biocontrol agents will only be released after it has been determined that they will not have negative impacts on the environment.

Until then, it is recommended that conventional chemical insecticides labeled for use on ornamental plants be applied to infested plants according to label directions.  Insecticides routinely recommended for use to control leaf-feeding caterpillars include carbaryl and acephate.  For those who prefer to use a non-toxic pesticide, Bt (Bacillus thuringiensis) sprays have proven to be effective against the larvae of various moths, including the nettle caterpillar.  Bt is not toxic to humans, other animals, and the environment.  Some formulations may also be used on organic farms.

For more information on the nettle caterpillar on the Big Island, please call the HDOA’s Plant Pest Control Branch in Hilo at: 974-4140.  For health issues related to nettle caterpillar stings, please call the Department of Health’s Vector Control Branch in Hilo at: 974-4238.

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