Little Fire Ant Infestations Found on Windward Oahu

Posted on Jul 18, 2019 in Main

July 18, 2019

HONOLULU – Infestations of little fire ants (LFA) have been detected in two areas of Windward Oahu. An infestation in Lanikai involving six residential properties is currently being treated by the Hawaii Department of Agriculture (HDOA) and the Hawaii Ant Lab (HAL). The other infestation area is located in an isolated area on Kualoa Ranch. LFA crews have been working with the ranch to survey the area and a treatment strategy is near completion. The area involved is about 14 acres in an area that previously underwent a native species restoration project and currently is not open to human foot traffic. A buffer zone of 20 acres is being planned for treatment, which will begin when the master treatment plan is finalized. Kualoa Ranch Land Stewardship teams have already begun treatment in applicable locations within the area.

Earlier this year, neighborhoods in Kaneohe and Ahuimanu were also found to have LFA and treatment of those areas continue. The sites are about half way through the treatment protocol and the last survey of both areas last week did not detect any LFA. LFA treatment plans are developed by HAL researchers and involves several types of pesticides and bait formulas which are applied on a six-week interval for a total of eight treatments. Monitoring of those areas will continue for several years.

In June 2014, an LFA infestation was detected in Mililani Mauka which covered six acres. A similar multi-agency response successfully eradicated the infestation and that neighborhood has been free of LFA since February 2015.

“Residents in uninfested areas around the state should always be on the look out for little fire ants,” said Phyllis Shimabukuro-Geiser, chairperson of the Hawaii Board of Agriculture. “Residents should also be careful before introducing any plants to their homes and yards regardless of where the plants are coming from. A simple peanut butter stick test can save your property from becoming infested with these invasive ants.”

LFA has been found on Hawaii Island since 1999 and the population is widespread on that island.

Since that initial detection, HAL and HDOA have developed a treatment strategy that has helped to prevent the spread of LFA to other islands.

HDOA and partner agencies, including the Invasive Species Committees on Oahu, Kauai, and Maui County and the Coordinating Group on Alien Pest Species (CGAPS) have been asking residents on Oahu, Kauai and in Maui County to survey their properties for LFA by using a little peanut butter on a chopstick and leave them in several areas for about one hour. Any ants collected should be put in a sealable plastic bag, placed in the freezer for at least 24 hours and dropped off or mailed to any HDOA office. An informational flyer may be downloaded at:

In addition, the Department of Land and Natural (DLNR) Resources has produced a three-minute video, “How to Test for LFA,” which shows the step-by-step procedure for testing for LFA. The video is available at:

Originally from Central and South America, LFA is considered among the world’s worst invasive species. LFA are tiny ants, measuring 1/16th inch long and are pale orange in color. Unlike tropical fire ants which move quickly and are established in Hawaii, LFA move slowly and are much larger with a larger head in proportion to its body. LFA can produce painful stings and large red welts and may cause blindness in pets. They can build up very large colonies on the ground, in trees and other vegetation, and in buildings and homes and completely overrun a property.

Suspected invasive species should be reported to the state’s toll-free PEST HOTLINE – 643-PEST (7378).

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