
Morus Alba (mulberry) trees
Morus alba trees used to harvest leaves for silk moths to feed on. Young silkworms need soft new leaves because their jaws aren't as strong yet. Silk moths can live on some other leaves as well, but morus is their favourite. An additional benefit is that morus trees are fast growing. Because Morus alba trees prefer warmer climates, growing silkworms is also bound to warmer climates.
Silkworm eating these morus leaves:

''Morus alba'', known as white mulberry, is a short-lived, fast-growing, small to medium sized mulberry tree, which grows to 10–20 m tall. The species is native to northern China, and is widely cultivated and naturalized elsewhere. It is known as शहतूत in Hindi,''Tuta'' in Sanskrit, ''Tuti'' in Marathi and ''Toot'' in Persian and in Armenian.