A shopper made a not so tasty discovery after buying fruit and veg at a Coles in South Australia, unearthing a family of caterpillars after chopping open a red capsicum.

Matthew Wilson posted a photo of his multi-legged find on Coles' Facebook page on Monday, joking that he "took some friends home with us" after visiting the Kurralta Park store.

The shopper said he would still eat the vegetable in his wife's "tasty chicken stir fry" but would probably look for "caterpillar-free red capsicum in the future".

"I would like to thank you for providing me with groceries that are indeed fresh," he said.

The post, which has been liked more than 7500 times on Facebook, has sparked a debate about the freshness of fruit and vegetables sold at the major supermarket chains.

One top commenter, Darian Bloom, said the presence of larvae in the crunchy capsicum was evidence of its freshness.

"How is Coles supposed to know there a bug in it? I think the standard at Coles is great," he said.

Another poster, Kevin Owen, said society was so used to having food presented in an appealing manner that "we've forgotten where our food comes from".

"Flick that little bugger out, give it a rinse and enjoy your chicken stir fry," he said.

"I reckon that's a pretty mint-looking capsicum, check out how thick all the way around it is."

Coles responded with good humour to the post, thanking Mr Wilson for finding the caterpillars safe and sound before they were cooked.

"We hope the joy of being new foster parents to this army of caterpillars brings you much warmth this winter," the supermarket giant's spokesman said.

The company said it would offer a full refund or replacement to help Mr Wilson get over his shock.

It's not the first time there has been customer angst over the perfection of the fruit and vegetables presented at major supermarket chains.

Woolworths rejects at least 25 per cent of market fruit and vegetables because of imperfections or cosmetic damage.

In an attempt to make better use of its imperfect produce, Woolworths has started selling its not-quite-right fruit and veg at cheaper prices.