The previous outbreaks were in 2012, 2013 and 2014, meaning there had been one incident per year since the introduction of the direct exit path at international airport borders for New Zealanders and Australians.
He said they would continue to find the odd fruit fly because they were still finding a little bit of larvae in fruit. Further larvae had been found in properties around the site of the original discovery of 39 larvae on fruit trees.
His confidence was based on the ministry's preparedness for such a breach. He said 160 people were working in Auckland and Wellington on the outbreak, including staff who were involved with the last major breach when 41 Mediterranean fruit flies were eradicated in 1996.
Mr Guy was visiting the heartland of New Zealand's $1.4 billion kiwifruit export market - an industry vulnerable to fruit fly incursions.
Growers were concerned that the latest outbreak could not have happened at a worse time because of the risk it posed to the movement of New Zealand fruit.
A total of 10 fruit flies had been found up to yesterday, and multiple discoveries of larvae that indicated the threat of a population being established.
Growers were expected to ask the minister to introduce the X-raying of all baggage arriving in New Zealand, particularly through the high-risk period from January to April-May. It would replace the system in which millions of passengers deemed to be low risk were exempted from baggage screening.
Mr Guy said the Ministry would review biosecurity procedures with its industry partners once the current outbreak had been dealt with. In the meantime sniffer dogs would continue to be deployed on all baggage looking for host fruit fly material before passengers exited international airport terminals.
He said there had been significant developments in the past 12 months with the Government/Industry Agreement that supported preparedness and biosecurity responses.
The partners were the kiwi fruit, pork, pip fruit and equine industries.
Mr Guy said New Zealand had shown itself to be one of the best countries in the world at eradicating pest incursions, with a multi-layered biosecurity system that focussed on risk.
The ministry had also focused on biosecurity processes used in Australia on the 22,000 tonnes of fruit and vegetables exported to New Zealand every year, including heat treatment, cold storage and fumigation.