Ministry for Primary Industries adviser Natalie Quirke said just one Queensland fruit fly had been found - a male discovered in a trap on May 8.
"There is no guarantee there will be more than one fly," said Quirke.
"Since 2006, the ministry has intercepted species of fruit fly 53 times at the border, preventing a population from establishing here. Additionally, the Queensland fruit fly has been detected twice before in New Zealand - in Northland in 1995 and in Auckland in 1996.
"In both cases increased surveillance found no further sign of Queensland fruit fly and there were no breeding populations present."
Yesterday biosecurity teams were checking traps and talking to residents in Zone A, which covered a 200m circle around Wolverton St.
Residents were asked not to take fruit or vegetables off their property.
Seventy other traps had been set up in the neighbourhood.
Samples of fruit from trees in 1.5km Zone B had also been taken for examination.
Horticulture NZ president Andrew Fenton said it was an "anxious time" for all growers.
Supermarkets within Zone B had signs up asking people not to buy produce unless they lived within the MAF boundary.