Eradication Efforts Begin to Combat Little Fire Ant Infestation in Waimanalo

Posted on May 15, 2014 in Main, News-Releases

May 15, 2014

HONOLULU — The Hawaii Department of Agriculture (HDOA) today began a multi-tactic treatment program to eradicate an infestation of little fire ant (LFA) in Waimanalo.  A six-person crew, including staff from the Hawaii Ant Lab, Oahu Invasive Species Committee and HDOA, began spraying a 6-acre area, which includes the 3.5 acre infestation area and buffer zone. The crews applied Tango® ((S)-methoprene in gel bait matrix), a growth inhibitor that worker ants take back to their nest to feed the queen ant, which reduces the viability of eggs the queen produces.

Next week, crews will return to the area to distribute a grandular pesticide, either Probait® (Hydramethylnon) or Siesta® (Metaflumizone), which will kill the ants.  In several weeks, the same process will be conducted using Tango® followed by the other grandular pesticide.  Research has found that alternating the use of Probait® and Siesta ® is more effective in eradicating LFA.

Earlier crews cleared transects, or pathways, through the brush so pesticide applications could be completed evenly over the area, which is located on state land near Waikupunaha and Kakaina Streets in Waimanalo.

The process will be repeated about eight times during a period of one year. Once no LFA are found, the area will be monitored for several years. All products being used are general-use pesticides.

“The research and techniques developed over the past years give us confidence that this infestation can be eradicated,” said Scott Enright, chairperson of the Hawaii Department of Agriculture. “The systematic approach makes sense practically and scientifically.”

No other sites on Oahu have been found with LFA.

HDOA continues to ask homeowners to help survey their yards for LFA by placing a chopstick smeared with a little peanut butter in the yard for about one hour, then place the stick in a sealable plastic bag and freeze the sample for at least 24 hours and then send it to the HDOA. Surveying instructions are available on the department’s website at:

LFA has been found on Hawaii Island since 1999. In late December 2013, LFA was detected on hapuu logs (Hawaiian fern) at retail stores on Maui and Oahu. Since its detection, Oahu and Maui nurseries have been surveyed. Five Oahu nurseries, three of which are in Waimanalo, were found to have small infestations of LFA, which were treated and are now clear of the ants.

Originally from South America, LFA is considered among the world’s worst invasive species.

LFA are tiny ants, measuring 1/16th inch long, are pale orange in color and move slowly. LFA move slowly, unlike the Tropical Fire Ant which is established in Hawaii, which move quickly 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 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).

For updated information on LFA in Hawaii, go to the HDOA website at:

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