Stinging little fire ants have appeared in several parts of American Samoa after initially being confined to just one place on Tutuila.
The Land Grant Division is trying to tackle the infestation and entomologist, Mark Schmaedick, said it was working with house holders to try and control the spread.
He said it had been established that the ants had been on the island for three to four years before anyone reported them.
"During that time various things may have been moved from infested areas out to other non-infested areas and the little fire ants may have been carried along with those items, so that is why we have been asking the families in the infested area whether they recall moving any items into other areas. Then we have been tracking those down and doing surveys."
Mark Schmaedick said the ants had a severe and painful sting and were hard to eradicate.