Fall armyworm has been found at two locations in the West Coast region, with 31 confirmed findings of FAW in Westland and Northland for the 2023/24 growing season to date.
But biosecurity officer at the Foundation for Arable Research (FAR) Ash Mills said there have been no finds in the rest of the country this growing season.
By this time last year there had been 45 confirmed finds spread across Northland, Auckland, Waikato and Taranaki, he said.
In December FAR confirmed that the first FAW was found in Northland and that this showed the pest had overwintered in the region.
According to Mills the new finds in Westland likely mean the pest overwintered in the area, but he could not be certain yet.
It could also have been windblown from Australia or Northland, he said.
He would have to study recent weather patterns to confirm the likelihood of this, he said.
“We will potentially see progression [of the pest] down through the country as we move through summer. The West Coast might be an anomaly, as on paper they should not survive winter. But there are pockets of microclimates in the West Coast [that would help survival],” he said.
Mills said fewer finds could be a result of a colder winter.
There could also be a level of underreporting as there is less of a panic around Fall armyworm than when it was first discovered, he said.
Because many crops were planted early in the season, and will be mature by the time the pest emerges, he expected less damage to crops this season, Mills said.
A FAR update said “it can be anticipated that the second-generation adults will begin to emerge resulting in a moth flight. Pheromone traps may indicate the presence of this new generation of moths; however crop scouting is key.”
Mills said once a moth flight occurs, FAR will have more insight into how far the worm will spread.
The worm populations appear to be small and localised, and are well below economic thresholds, he said.