Cockroach breeder Wang Fuming said business is booming for his cockroaches.

The demand comes from China's pharmaceutical companies, who use the cockroaches in pills to treat illnesses afflicting the stomach, liver and heart.

Wang said he has a special relationship with the cockroaches.

"I love these cockroaches, I feel very close to them," he told CNN.

"Just smell that unique smell they have."

In an industrial district on outskirts of the city of Jinan in eastern China, Wang farms millions of cockroaches.

He keeps the roaches in warehouses with narrow corridors and hives made of cement roof shingles.

There, visitors are greeted by the strong smell of ammonia and the sound of scuttling legs.

Wang breeds American cockroaches and he sells them to pharmaceutical companies in China by the ton.

Insects, including cockroaches, are a valued ingredient of Chinese medicines with its use stretching back more than 5000 years.

The United Nations published a report in 2013 recommending insects for human consumption as an alternative source of protein that can be less harmful to the environment than meat.

Wang said he doesn't need to be convinced of the merits of eating cockroaches.

"If you don't try it you'll regret your decision forever," he said.