Horticulture New Zealand chief executive Peter Silcock told the Herald on Sunday it was "a huge worry" but was satisfied with the biosecurity response.
The country exports about $2.5 billion worth of fruit and vegetables a year to trade partners including Asia, the United States and Europe, he said. These regions have no present requirement to screen for Queensland fruit fly.
"A worst-case scenario is for those markets to ask for our products to be treated," he said.
"The cost of doing this would significantly raise prices of our fruit and vegetables for export and affect businesses and jobs across the country. More flies being found is a concerning development but not completely surprising."
Luggage of international arrivals at airports will now go through more x-raying and detector dogs will screen all passengers and luggage.
Residents within the controlled area of Grey Lynn, Western Springs, Mt Albert, Ponsonby and Kingsland are still restricted from taking fruit and vegetables outside of the area.
The current fruit fly find is the worst outbreak since 1996, when Mediterranean fruit flies were found in the Auckland suburb of Mt Roskill.