Little Fire Ant eradication project on Kauai
a repository of information about invasive ants

At the same time as LFA were first detected on the Big Island, a small infestation was also found on Kauai.  Some mature palm trees had been moved from the Big Island to a property near Kalihiwai and one of the palms was contaminated with Little Fire Ants.  At the time (1999) the HDOA acted very quickly by treating the infested palm tree and it seemed they were eradicated.

A few years later, LFA were again found at the same location but now had spread over most of the property.  By 2012, the infestation had reached about 12 acres in size, despite a huge effort by HDOA staff to contain the infestation.  At this time, HAL had developed new tools and techniques that allowed us to successfully treat the LFA colonies in the tree canopy.  An eradication program started at that time and is still running in 2016.

Eradication LFA from Kauai was a top HAL priority.  If they were to spread around the island, the impacts would be catastrophic!  By far, this is the most ambitious program HAL had ever undertaken.  The infested site had several impenetrable thickets of “hau” (Hibiscus tilliaceus) as well as a vertical cliff that ran from the ocean to a height of around 140ft.  By all accounts, this project should have failed.  But, so far, we’re on track.

We decided to split the project into two phases - the accessible area at the top of the cliff (about 10 acres) and the very steep cliff section (about 2 acres).  The project was conducted under an experimental use permit for pesticides because some of our treatment methods were different from the instructions on the pesticide label.  Phase 1 commenced in 2012 and phase 2 commenced in 2014.

There were a lot of things we needed to work through before we could tackle the steep area.  First, it was adjacent to the ocean and regulations for the use of pesticides in that area were being altered (we had to wait while this was finalized).  Access was very perilous, so we needed to hire a climbing company to train the HAL staff in rappelling as well as have the company assist us with treatment. Finally, we needed to obtain a Special Local Needs Permit to use one of the pesticides we applied.

As of early 2016, everything looks very promising.  The follow-up surveys have not detected any ants remaining - either in the phase 1 or phase 2 areas (we have two very small “hotspots” that we continue to treat).  Further follow-up monitoring is crucial to ensure we have not missed and small incipient colonies, and we expect by 2017-2018, no LFA will remain on Kauai.
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This project is a multi-agency response which includes valuable contributions from the Kauai Invasive Species Committee, Hawaii Department of Agriculture, county of Kauai, Climb Aloha and many others