LEPIDOPTERA. 223 



different movements the animal emerges from its skin, which remains 

 held up by the silken threads. The duration of the time occupied 

 in moulting varies with the degree of the heat or humidity of the 

 atmosphere ; but in general the state of sleep lasts from twelve to 

 twenty-four hours. One hour after the crisis the worm begins again 

 to eat. 



The ages of the silkworm are the periods of time which elapse 

 between one moult and another. If we observe some silkworms 

 when the temperature is favourable, we shall find that there 

 are four moults, and consequently five ages. At the first 

 age (Fig. 204), the silkworm is black and hairy; then of a 

 nut colour at the moment when the first moult is going to 

 take place. " The appearance presented by these worms Fig. 204. 

 collected together on a leaf," says Dandolo, "is that of a Egg ag e 

 downy surface of a dark chestnut colour, in the midst of 

 which one sees nothing but a movement of little animals having 

 their heads raised, working them about, and presenting black, shiny 

 muzzles. Their bodies are completely covered with hairs arranged 



^ 



Fig. 203. Fig. 206. Fig. 207. 



Second age. Third age. Fourth age. 



in straight lines, between which one perceives along the whole 

 length of the body other longer hairs.* 



The first age lasts for five days. At the second (Fig. 205), the 

 worm is grey, almost without down, then of a yellowish white, and 

 one sees the crescents making their appearance on the second and 

 fifth segment. At the third age (Fig. 206), there is not a single hair 

 remaining, and the worm becomes whitish, and is always becoming 

 lighter. The third age lasts six days, as does also the fourth (Fig. 207). 

 At the fifth (Fig. 208), the worm has very nearly reached the end of 

 its career in the caterpillar state, and now is the time of its greatest 

 voracity. This age is the longest ; it lasts nine days. 



At each of these periods in the life of the silkworm may be 



* " L'Art d'elever les Vers a Sole," par le Comte Dandolo. In 8vo. 2e edi- 

 tion. Lyon, 1825. 



