A cereal prankster has been targeting letterboxes around Blenheim, dropping off low-fat muesli bars in a bizarre spree which has lasted more than a year.

The motives of the perpetuator remain unclear, but it is safe to say public health is not high on the agenda considering the contents of the Weight Watchers bars.

Inside each of the wrappers, which have been meticulously resealed with glue or sellotape, residents have been bemused to find a roll of cardboard.

Paul Negrerie, a French winemaker working in Marlborough, said he first encountered the misleading muesli bars in January, after moving into a flat on Maxwell Rd.

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"I picked it up from the letterbox and thought, 'sweet, a free muesli bar,' but when I opened it up it looked weird," he said.

"I thought it was an advertisement for a muesli bar or a gift, but it was just cardboard."

His former flatmate, Blenheim chef Dom Chan-Roberts, said the hoax bars were being dropped off before he moved into the house last August.

The first time he encountered one Chan-Roberts put it down to the fact one of his flatmates might have asked for a nutritious snack from a workmate.

It was not until a packet of cigarettes was dropped off, presumably by the same person, that he realised the persistent efforts of the prankster, which involved a bar being dropped off in the letterbox every few weeks.

The packet contained a bunch of hand-rolled cigarettes taped onto Marlboro brand filters and painstakingly filled with grass.

"They had gone to extreme lengths," Chan-Roberts said.

"It's a good laugh, but if they've got this much time on their hands, they should be doing something more productive."

He and his partner had speculated about the motives of the prankster, figuring they must be a former resident of the house.

"We reckon it would have to be a crazy person who used to live at the house and thought, 'there's new people living here, so I'm just going to keep trolling them.'"

However, other Blenheim residents had also reported strange bars left in their letterboxes, raising the spectre of something more obsessive.

University of Otago associate professor Martin Sellbom, from the Department of Psychology, hesitated to comment on the case without firmer evidence.

Without interviewing the muesli bar prankster Sellbom said his analysis would be comparable to the attempts of FBI criminal profilers or Hollywood movies, somewhat lacking in scientific proof.

"The thing is it could be more than one person, we don't know how many people are involved, maybe there's some mass production of these Weight Watchers bars," he said.

"Given it has been going on for quite some time, there seems to be some form of incentive or reward that the person or persons doing this are getting from the behaviour.

"What that is I have absolutely no idea, there's no scientific research that would point to particular issues."

However, Sellbom said he could not rule out psychological disturbance, or other theories that the prankster was trying to send a message about healthy eating by promoting Weight Watchers.

"As a psychologist, one has to pick horses not zebras, I would say it's more likely to be some form of elaborate prank instead of any kind of psychological disturbance, although that can't be ruled out."

A Weight Watchers spokeswoman said the bars were not part of a marketing stunt.

"Although it certainly exposes people to the brand, we think that they might like the bars more if they got to experience the deliciousness that's normally inside," she said.



Blenheim police community constable Russ Smith said the issue had not been brought to his attention, but said he would be happy to talk to anyone if they had concerns.

However, he said it was uncertain whether the behaviour was actually illegal.

"If they were trying to defraud someone or poison them, or if they were stealing the bars then that would be criminal."

"But it could just be a 7-year-old kid who thinks it's a laugh.

"It seems a bit weird."