A cocoon is a hierarchical laminated composite consisting of layers, which can be categorised broadly from their layers into single and double cocoon, as shown in Fig. 3. The single cocoons can consist of just one single layer (e.g. Actias and Cricula cocoons), or multiple layers deposited in sequence by the silkworm with either weak or strong bonding between the layers. These multiple layers are parallel to the surface direction, and there are relatively weak bonds by sericin between them. They can be either easily peeled (e.g. B. mori, A. pernyi), or can be separated through a degumming method (e.g. Saturnia pyri, Opodiphthera eucalypti) because of the relatively stronger bonding between the layers. Most of the double cocoons studied in this project have an intervening mesh layer bonded between outer and inner cocoons (e.g. H. cecropia, Callosamia promethea). Sometimes the silkworm could also create a large and irregular outer ‘bag’ enclosing an inner cocoon without any bonding between the two cocoons (e.g. Antheraea roylei).