226 THE INSECT WOELD. 



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 one observes some silk- 

 worms 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 

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

 Fig. 204. downy surface of a dark chestnut colour, in the midst of 



Egg and " 



first age. 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 in straight lines, between which one perceives 

 along the whole length of the body other longer hairs."* 



Fig. 205. Fig. 206. Fig. 207. 



Second age. Third age. Fourth age. 



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. 



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

 Lyon, 1825. 



