An explosion in army worms is threatening farmland in the northern half of the North Island. Northland is affected for the second consecutive season.
Farmers are advised to check for signs of the pest, which gets its name from the the way the worms move across the ground in formation, eating any grass and crops in their path.
DairyNZ farm systems specialist Phillipa Hedley says seasonal conditions have caused a population explosion of army worms in an area extending from Northland to southern Waikato and eastern Bay of Plenty.
The army worm can grow up to 50mm in length and has a voracious appetite for plant material.
It is clearly visible as it moves across farmland.