Northern leopard frogs are fed a diet of crickets, mealworms, waxworms, or silkworms. The eggs hatch and the caterpillars (silkworms) are fed fresh mulberry leaves. Thai silk () is produced from the cocoons of Thai silkworms. In order to kill the silkworms, the cocoons are dried in the sun. So mulberries were planted for rearing silkworms. Various scorpion, spider and insect species include the commercially useful honeybees, silkworms and lac insects. Extracting raw silk starts by cultivating the silkworms on mulberry leaves. Afterwards, they accept house flies and larger insect prey including crickets, locusts, silkworms, and cockroaches. Trade with China via the Silk road introduced silk textiles using domesticated silkworms. Vineyards, orchards, and mulberry groves for silkworms are developed in the valleys. Cultivation of white mulberry for silkworms began over four thousand years ago in China. The leaves of the mulberry provide food for the silkworms used in commercial silk production. Selected mulberry trees are grown to act as homes for the silkworms. Genetic modification of domesticated silkworms has been used to alter the composition of the silk. Their oldest occupation was rice-growing, but they also raised silkworms and cultivated tobacco.