The Hawaii Department of Agriculture released details on Friday of the plan that has been developed to eradicate the little fire ant (LFA) infestation in Waimanalo.
The multi-step plan includes preparing access routes for treatment, multiple applications of several types of pesticides over a period of one year, pesticide monitoring and continued surveying of the area. The infested area is estimated at three-and-a-half acres. The total treatment area, including a buffer zone, will cover six acres.
"We're fairly confident we can eradicate. It's a small enough infestation that using the method developed by Hawaii Ant Lab that has actually proven to eradicate infestations of the same size. We're certain we can eradicate it," said Rob Curtis of the HDOA.
An extensive survey was conducted earlier this month covering more than 50 acres from Kumuhau St. to Mahailua St. in Waimanalo. The survey collected about 1,500 samples, of which 60 were positive for LFA.
The infestation area is confined to state land and in mulch areas located outside of nurseries in that area. LFA was detected previously on hapuu from Hawaii Island a few nurseries and garden shops earlier this year, but those areas were treated and are now clear of LFA.
"Eradication plans require good preparation and methodical planning," said Scott Enright, chairperson of the Hawaii Board of Agriculture. "We can’t just go into an infested area and just spray pesticides – there’s a science to it."
Since the survey was conducted, crews from HDOA and the Oahu Invasive Species Committee have contained the infested area and have been working on habitat modification, by preparing the area and clearing access paths for treatment.
HDOA and the Hawaii Ant Lab have developed a treatment plan which will begin in mid-May using a combination of pesticide baits, including Tango ((S)-methoprene in gel bait matrix), Probait (Hydramethylnon) and Siesta (Metaflumizone). These pesticides are general use pesticides.
The area will be treated at least eight times over a 12-month period. If the area is clear of LFA at the end of the 12 months, eradication efforts will transfer to monitoring for three years.
HDOA's Pesticides Branch will take water samples from the stream throughout the treatment period to test for pesticide residue.
"We've got a number of ants here and its probably one of the responses people say, 'It's just an ant. We've got ants.' Well, this ones dfferent. It needs to be treated differently. We really wait to see people call us in so we can respond and see, hoping its not the right ant [and] its one of thee others that aren't so bad.," said Neil Reimer of the HDOA. "If we catch it too late then it's too late to be able to do anything about it."
HDOA, and partner agencies are continuing to follow-up on leads of other potentially infested sites on Oahu. No other sites have been identified so far.
Homeowners may help the state survey their yards by placing a chopstick smeared with a little peanut butter in the yard for about one hour and put 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 http://hdoa.hawaii.gov/pi/files/2014/01/Survey-LFA-public-2014-01-29.pdf
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 were in Waimanalo, were found to have small infestations of LFA, which were treated and are 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 http://hdoa.hawaii.gov/pi/main/lfainfo/