Rearing of silkworms:
Rearing of silkworms is the first and crucial step in sericulture. It involves the cultivation of silkworms in a controlled environment. This process begins with the selection of healthy silkworm eggs, which are carefully incubated on special trays or paper sheets. The eggs hatch into larvae, which are then placed on mulberry leaves for feeding. The silkworms undergo several stages of growth, molting their skin multiple times before reaching the cocoon stage.

Harvesting of silk:
After the silkworms have completed their growth and formed cocoons, the harvesting process begins. The cocoons are carefully collected, and the outer layer of the cocoon, which is made of silk fibers, is extracted. This extraction is typically done by boiling the cocoons in water, which softens the silk fibers and allows them to be easily unwound.

Spinning of silk:
Once the silk fibers are extracted from the cocoons, they are spun into silk threads. This process involves carefully unwinding the silk fibers from the cocoons and combining them to form a single thread. The silk threads are then spun onto reels, creating long strands of silk that can be used for various purposes.

Dyeing of silk:
Dyeing of silk is the process of adding color to the silk threads or fabrics. It is done after the silk has been spun into threads or woven into fabrics. Dyeing can be achieved using natural dyes extracted from plants, insects, or minerals, as well as synthetic dyes created chemically. The dyeing process involves immersing the silk in a dye bath or applying the dye using various techniques to achieve the desired color and pattern.

Explanation:
Among the given options, the process of dyeing silk (option D) is not directly involved in sericulture. Sericulture primarily focuses on the cultivation of silkworms, harvesting their cocoons, and spinning the silk fibers into threads. Dyeing is a separate process that occurs after the silk has been obtained and processed. While dyeing is an essential step in the production of colored silk products, it is not directly related to the sericulture process itself.