If it is a young silkworm hatched from eggs, use very tender mulberry leaves. When they grow up, some silkworms will eat lettuce leaves, but some silkworms will not eat them because they are not used to it.

But silkworms like to eat mulberry leaves best, because silkworms eat mulberry leaves most of the time, and their children and grandchildren multiply on mulberry trees from generation to generation, gradually forming the characteristics of being most used to eating mulberry leaves, and they are inherited.

Extended data:

Silkworm is a kind of abnormal insect, the most common one is silkworm, also called silkworm, which is one of the economic insects that cocoon on mulberry leaves. Silkworm originated in China, its development temperature is 7 ~ 40℃, and its suitable feeding temperature is 20 ~ 30℃. Silkworm babies feed on mulberry leaves After eating mulberry leaves continuously, the body turned white and began to peel after a period of time. When peeling, they don't eat or move like sleeping for about one day. This is called "dormancy". Once skinned, it is the second instar larva. Even if it is peeled once, it will increase by one year, and the larvae will be peeled four times to become fifth instar larvae. After eating mulberry leaves for 8 days, they will become mature silkworms and start spinning and cocooning.

References:

Life habits of silkworms Baidu Encyclopedia