A supermarket chain is investigating its own brand after a Christchurch man discovered live bugs in a bag of Pams Corn Chips on Saturday night.

Trevor Cundall had eaten a bag of the chips before pouring another bag into a bowl to share with his family when he discovered four bugs "alive and wriggling", The Press reported.

Foodstuffs Own Brands, which owns the Pams brand, would investigate the matter, a spokesperson said.

The chips were bought at Pak 'n Save, Moorhouse, on February 6 and were due to expire on June 10.