"We are working with authorities in the United States to identify the source of the contamination and possible treatment options for consignments on their way to New Zealand."
Spotted wing drosophila are native to India, Korea, Japan and much of South-East Asia. They are also found across much of North America and Western Europe.
Biosecurity NZ says the flies are a particular risk as they can lay eggs in fresh fruit before it is even picked. They can damage berries, stonefruit and grapes.
"If they invaded New Zealand, all commercial and home growers would face increased pest control costs and lowered crop yields."