A stick insect (C), declared the world's longest insect, pictured with other smaller ones at the Insect Museum of West China in Chengdu, southwest China's Sichuan province, in an image taken on June 28, 2015 and released to AFP on May 6, 2016

A bug over half a metre long discovered in southern China has been declared the world's longest insect, Chinese state media says.

A measuring 62.4 centimetres found two years ago in the southern province of Guangxi has broken the record for length amongst the world's 807,625 known insects, the official Xinhua agency said Thursday, citing the Insect Museum of West China.

The previous record-holder was a Malaysian 56.7-centimetre-long stick insect discovered in 2008 and now on display in London's Natural History Museum.

Tipped off by locals about a huge beast half a metre long but as thick as a human index finger, scientist Zhao Li had been on the hunt for the for six years before he finally glimpsed and captured one.

"I was collecting insects on a 1,200-metre-tall mountain in Guangxi's Liuzhou City on the night of Aug. 16, 2014, when a dark shadow appeared in the distance, which looked like a tree twig," Zhao said, according to Xinhua.

"As I went near, I was shocked to find the huge insect's legs were as long as its body," he added.

One of the offspring of a record-breaking stick insect at the Insect Museum of West China in Chengdu, southwest China's Sichuan province, in a picture taken on August 31, 2015 and released to AFP on May 6, 2016

The bug has been dubbed Phryganistria chinensis Zhao in his honour, and a paper about it will soon be published.

More than 3,000 varieties of stick have been discovered so far, Xinhua said.