The growing Chinese cities generate much more food waste than they can handle in landfills. In this regard, the Chinese invented that cockroaches can help in the disposal of this waste.

It is estimated that there are about 100 cockroach farms in China. They are bred in specially designated rooms. When the cockroaches die, they are used as feed for farm animals. Some use dead cockroaches in the pharmaceutical industry (e.g. for the treatment of stomach diseases) or cosmetology for beauty treatments.

A billion cockroaches are fed 50 tons of food waste per day. This is equivalent to the weight of seven adult elephants.

You can find more details in the article: https://www.businessinsider.com/chinese-city-feeds-cockroaches-kitchen-waste-2018-12?IR=T#cockroaches-are-a-bio-technological-pathway-for-the-converting-and-processing-of-kitchen-waste-said-liu-yusheng-president-of-shandong-insect-industry-association-4