Tasman District Council biosecurity co-odinator Lindsay Vaughan is questioning research findings that suggest invasive ant populations die off without human intervention.
Victoria University scientists have found that infestations of Argentine ants, which arrived in New Zealand more than 20 years ago, have often collapsed and disappeared without eradication measures.
They think diseases or parasites rather than climatic factors could be responsible.
They say that offers the potential for big savings in biosecurity costs and the possiblity of finding biological controls..
But Lindsay Vaughan says there's no evidence that colonies of Argentine ants in Nelson, Stoke and Richmond are collapsing naturally.
He says ant colonies move on after depleting food sources in an area and that can also skew survey findings.
As well as being an urban pest, Argentine ants are a threat to horticulture because they farm scale insects and aphids that damage crops.