20 HISTORY OF INSECTS. 



the reign of Charles I., a third in that of George I., and a 

 fourth very recently (1825), both in England and Ireland; 

 but all these have proved unsuccessful, and it is now gene- 

 rally beheved that our chmate is not suited for the purpose. 

 Although the production of silk in England is abandoned, 

 yet its manufactiu-e in this country is carried on to a prodi- 

 gious extent, furnishing employment for more than five 

 hundred thousand human beings. The quantity of silk an- 

 nually consumed in England alone, amounts in weight to 

 four millions of pounds ; in France, Germany, Italy, Tur- 

 key, and the continent of Asia, it is also an article of great 

 commercial importance. 



Silk is spun by a caterpillar called the silk-worm, which 

 feeds on the leaves of the mulberry-tree : this caterpillar is 

 produced from eggs, laid by a moth in the autumn of the 

 preceding year. In May the eggs are hatched, and pro- 

 duce small black caterpillars less than the tenth of an inch 

 in length ; these daily increase in size, and gradually alter 

 their colour till they become nearly white. 



In this country the caterpillar takes fifty-six days to ar- 

 rive at perfection, during which time it invariably sheds its 

 skin as many as four, and occasionally five times ; the cause 

 of this occasional additional change is not known. After 

 every change the caterpillar is lighter in colour, and has a 

 larger head, than previous to the change ; it spins during 

 five or six days, making about sixty-two days passed in the 

 caterpillar state. In warmer chmates the catei-pillar arrives 

 at its full growth in forty- seven days, and has finished spin- 

 ning in five more, making together fifty-two days; these 

 may be reckoned thus : — from the hatching to the first 

 change, seven days ; changing, two days ; between the first 

 and second change, seven days ; changing, two days ; be- 

 tween the second and third change, seven days ; changing, 

 three days ; between the third and foiu-th change, seven 



