Aaron Sutherland (23) bought the 1kg bag of mandarins from Countdown supermarket in Andersons Bay for $5.98.
But he has yet to sample his purchase.
When he opened the first mandarin, two 1cm-long worms popped their heads out.
The rest of the fruit was infested with a black fungal mass and what appeared to be insect eggs.
"I was still in the Countdown car park and unpeeled one for my 20-month-old boy, Liam, because he loves them. It was lucky I did, because if Liam had peeled it himself he'd have just shoved it in his gob," Mr Sutherland said.
"But I couldn't believe it when I saw there were two worms moving around on it. I was completely disgusted and speechless.
"I took them straight back in and complained, but the Countdown staff just fobbed me off. They weren't apologetic at all. They just acted like it was an everyday occurrence.
"They told me to leave them there and that they'd replace them, but I reckon they just wanted to keep the evidence. It makes you wonder how many other people have gone back with bad fruit and it's ended up just being thrown in the bin," he said.
"I don't think that's anywhere good enough - $6 is top dollar for a kilo of mandarins."
Biosecurity New Zealand spokeswoman Helen Keyes said as the mandarins were grown in New Zealand, they were not subject to importation regulations.
The Satsuma mandarins were marketed and distributed by Freshmax Ltd.
However, nobody from the Freshmax Christchurch office was available to comment on the infestation yesterday afternoon.
The manager of Countdown Andersons Bay, Ron Andrew, also declined to talk when contacted by the Otago Daily Times yesterday, referring comment to Progressive Enterprises' media liaison office in Auckland.
Media relations manager Penny Newbigin told the ODT Mr Sutherland would be offered his money back and a replacement bag of mandarins.
"We have a '100% fresh or it's free' policy. If the customer can take them back to the store, we will give him a replacement product and his money back," she said.
Mr Sutherland was satisfied when told of the outcome last night.
"I just wanted someone to say 'sorry'. That was what annoyed me," he said.
"They were treating it as though it was my problem."
