By last night it had confirmed that one fly, 39 larvae and one pupa had been found at the first property.
The ministry expects to find more eggs, larvae, pupae and adult fruit flies in the coming days - but it says aerial spraying is not needed at this stage.
Those living in the affected areas are banned from taking fruit and vegetables outside the zone
If the outbreak spreads it could be hugely damaging for the industry as the Queensland fruit fly can make fruit and vegetables inedible.
Even if the fly doesn't do that much damage it can increase treatment costs for the billions of dollars worth of annual exports.
Horticulture New Zealand chief executive Peter Silcock described it as "a huge worry" but was satisfied with the biosecurity response.
"We are very happy with what [the ministry] is doing to contain and deal with the problem, and the response from the public has been fantastic."
The country exports about $2.5b 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."
Labour biosecurity spokesman Damien O'Connor echoed fears for businesses if the fruit fly problem spreads.
"This is the first time New Zealand has had a population of the Queensland fruit fly and every step possible must be taken to eradicate this pest," he said. "Labour urges local residents to work with Ministry of Primary Industry officials, and recheck their gardens and fruit bowls to ensure no stone is left unturned.
"We have proved in the past we can eradicate such pests but the Government has to ensure officials are properly resourced to do so again." A spokesperson for the ministry said it was set up to "catch fruit flies and keep on trapping any that are out there, until we catch no more and can confirm the population has been eradicated".
The current fruit fly find is the worst outbreak since 1996 when Mediterranean fruit flies were found in the Auckland suburb of Mt Roskill.
Boastful little pest has plenty to say
By Cherie Howie
Grey Lynn's most wanted - the Queensland fruit fly - has opened its own Twitter account.
Parody account @greylynnfruitfl posted its first message on Thursday, two days after a trapped male fruit fly led to a fruit and vege lockdown over much of the city-fringe suburb.
The Twitter newbie came out swinging. Its first tweet was a jab at the man whose ministry wants it dead.
"[Primary Industries minister] Nathan Guy can kiss my sunburned Aussie arse," the brash Aussie interloper boasted.
The sassy pest tweeted: "I only came here to get away from that tool [Australian Prime Minister] Tony Abbott. You'd think that the lentil-loving lefties of Grey Lynn would support that."
A stopover in socialite Sally Ridge's garden proved a knockback, and had the fruit fly considering "hand[ing] myself in", but there were also plans to "catch a westerly breeze to Remuera and crap on [broadcaster] Mike Hosking's Ferrari". Penning erotic travel stories - 50 Shades of Grey Lynn - was also on the agenda.
As news broke that two more fruit flies had been found in Grey Lynn, @greylynnfruitfl was ready to offer Campbell Live host John Campbell an exclusive interview "in exchange for sanctuary".
