The silkworm is the larva or caterpillar of the domesticated silkmoth, Bombyx mori. It is an important economic insect since it is the producer of silk. A silkworm's preferred food is white mulberry leaves, but it may also eat the leaves of the Osage Orange or the Tree of Heaven. It is entirely dependent on humans for its reproduction and no longer occurs naturally in the wild. Sericulture has been practised for at least 5,000 years in China.