INSECTS IN COMMERCE 135 



five days old, it becomes grey in colour, and 

 is much less hairy, while crescent-shaped mark- 

 ings begin to appear on the second and fifth 

 segments. After the second moult all the hair 

 disappears, and the silkworm is perfectly 

 smooth; with each succeeding moult it grows 

 lighter in colour, until with the final casting of 

 its skin it is almost white. 



The caterpillar stage of the silk Moth lasts 

 for about eight weeks ; during all this time it 

 feeds voraciously, except just before each moult, 

 when it becomes lethargic and ceases to eat ; 

 and its skin becomes somewhat transparent and 

 wrinkled, and changes to a yellowish tint. The 

 silkworm then fastens a few threads to some 

 projecting object within its reach and, slipping 

 underneath them, begins to twist and writhe 

 until the skin bursts, when in a short time it 

 frees itself from its old garment, leaving it 

 caught up in the silk threads. 



The period of moulting is a very critical one 

 for the silkworm, which occasionally dies 

 during the process ; when it has come safely 

 through the moult it is in a very exhausted con- 

 dition, and remains motionless for a short time 

 in a state that has been likened to sleep. While 

 in this torpid condition the silkworm assumes a 

 very curious, characteristic position, with its 

 head and fore-legs raised. 



When the silkworm is full fed and ready to 

 change into a chrysalis, it ceases to eat, and its 

 skin becomes yellow and transparent. It then 

 begins to wander about looking for a convenient 

 spot in which to pupate, raising its head and 



