BEE experts believe the deadly varroa mite has been in Newcastle, in the NSW's Hunter region, since the summer.
"It's difficult to ascertain exactly how long they have been here but, given the populations of mites in some hives, it's likely they have been here since summer," said Dr Schouten, who specialises in honey bee research.
Asked if this cast doubt over where the outbreak began, he said: "Newcastle is the epicentre based on the data from surveillance so far".
One beekeeper said a NSW Department of Primary Industries [DPI] biosecurity officer told him modelling suggested the parasite would have "been here for longer than six months before it got to the sentinel hives [used for early detection of diseases and pests]".
The NSW government's emergency order for the crisis stated that varroa mite was first detected at "two properties in Mayfield and Mayfield West" on June 22.
One of these sites contained sentinel hives at the rear of a property in Mayfield, near the Hunter River and Port of Newcastle.
Insiders said the other site was a commercial bee operation, from which the mite had spread to other places in NSW.
This operation has been described in the beekeeping community as "ground zero" of the outbreak.
How the mite found its way to Newcastle remains an unanswered question.
Dr Schouten said the mites would have "arrived via a cargo ship or via illegal importation of queen bees".
"The data will show what country they have come from, which will assist in answering this question."
The NSW DPI has stated it will trace all movements of hives and equipment "over the past 12 months" on and off properties in the 50-kilometre emergency zone around Newcastle.
This made beekeepers suspect the parasite had been in Newcastle for some time.
DPI did not respond to questions about this issue. On its website, DPI said: "Tracing is a critical part of every response and is a focus for us as we eradicate varroa mite in NSW".
"Sourcing 12 months worth of data around the acquisition of honeybees from the Newcastle area will ensure we have all the information we need to continue this surveillance work."
Some beekeepers believe DPI won't be able to eradicate the mite. No country has managed to do so before.
There's also concern that DPI doesn't have enough people on the ground to euthanise bees and destroy hives in enough time to stop the spread. When one beekeeper tested his hives and found them to be positive, it took DPI four days to double check the result.
"Then it took them another three days to kill the bees and another two days to destroy the hives and remove them."
The beekeeper added that he was surprised that five people - instead of one or two - were sent to his site to double check the result.
Asked how many people DPI had working on the response plan to euthanise bees and destroy hives, a spokesperson said: "This varies daily but on Wednesday we had 147 people on duty, including five industry liaison officers, and 34 others which includes volunteers". On Thursday, they had "17 teams in the field, consisting of 95 personnel".
Asked how long the DPI estimated the euthanising of bees and hive destruction would take, the spokesperson said: "While we are on a program to eradicate varroa mite in Australia, we will continue to euthanise infested honeybees and hives".
DPI had been more optimistic on Monday, saying it had "a good opportunity to eradicate this biosecurity threat and stop the onset of the varroa mite".
"DPI has put significant measures in place to arrest the spread of the threat."
By Wednesday, new detections had occurred in the Hunter at Berry Park, Heatherbrae, Seaham and Hinton, bringing the total number of infested premises to 28.
By Thursday, new detections had occurred in the Hunter at Campvale, Holmesville and Glen Oak. This brought the total number of infested premises to 34.
DPI has been euthanising bees and destroying hives. By 6pm on Wednesday, honeybees in 1270 hives had been euthanised. By 6pm on Thursday, honeybees in 1693 hives had been euthanised.
On Thursday, the DPI had 11,124 hives registered within eradication zones.
It has been an emotional time for beekeepers.
David Vial, vice president of Hunter Valley Amateur Beekeepers Club, had his bees euthanised on Thursday. He ran a business breeding queen bees and selling bees at Williamtown, with about 150 hives.
"I've lost my whole business - all my hives and genetics from the queen bees. I'm broken," he said.
He went for a drive when the killings took place, saying "I couldn't be there".
Before he left, he said goodbye to his bees.
"It's been part of my life for 20 years and it's all come to an end. It's terrible."
Mr Vial will even miss bee stings.
"It's usually my fault because I've done something wrong. They're just busy doing their own work."
DPI officials offered to save his best queen bees, but he rejected the offer.
"We're not going to be able to have bees back here for a couple of years, so I couldn't see the point."
He told them: "Just do it. Put me out of my misery."
Bees are gentle creatures and "the most organised society on the planet". "If this mite gets out, we could lose up to 90 per cent of our bees. A lot of people don't realise the importance of bees."
Honeybees are crucial pollinators for crops including almonds, apples, avocados, blueberries, macadamias, pumpkin and watermelon.
Neil Livingstone, of Mayfield West, said the situation was "very emotional", as he was passionate about bees and loved them.
"I'm looking at $50,000 worth of bees being annihilated in the next few weeks. That's a kick in the guts when you're a retiree and you're using that as a supplement for the pension," he said.
He said it was unclear what amount of compensation the government would pay.
Mr Livingstone, a honeymaker, has hives spread across various sites in the Hunter. He said 12 of his hives had tested positive and 10 negative.
The positive hives were at Mayfield, Warabrook and Duckenfield [near Berry Park] and the negatives at Stockrington, Cardiff and Waratah.
"This cold winter is in the government's favour. The bees like to stay nice and warm and stay home. If they don't have a handle on positive hives by September 1, we're in trouble," he said.
"They'd never contain it in spring. September/October is the busy time for bees. Our food supply needs pollination and there will be no bees around. That's the scary thing. If it gets out, the rest of Australia will be in trouble too."
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