In 1867, Trouvelot studied and recorded the cocoon spinning behaviour of American silkworms [8], [9] and [10]. Yagi in 1926 categorized the cocoons according to their appearance [11]. Yagi divides the Saturnian cocoons into four types according to their modes of attachment and the formation of the exit hole for the adults: 1) stalkless and closed; 2) stalked and closed; 3) stalkless and opened, and 4) stalked and opened [11]. The cocoons discussed in this paper belong to the first, second and the third type. Some caterpillars spin completely closed cocoons and emerge by secretion of a fluid that softens and dissolves one end of the cocoon, e.g. B. mori, Antheraea frithi, while some larvae construct an emergence valve on the cocoon by spinning parallel strands of silk in a conical shape, e.g. Hyalophora cecropia, Cricula trifenestrata. The moth can push the strands apart to emerge, but the sticking fibres around the valve resist forced entry from the outside.