18 THE CULTURE OF THE MULBERRY SILKWORM. 



Wise precaution having been taken to destroy germs of disease in 

 the rearing room, the new-born worms may now be safely installed 

 there. 



Space required. 



The worms from 1 ounce of eggs should cover at birth 1 square yard. 

 Doubling this space on the fourth day, they would require "2 square 

 yards, and at their change of beds after molting, 4 square yards. By 

 the spacing of the third day of the second age, and the doubling of 

 beds preceding the second molt, they will need for the second age 8 

 square yards. For the third age 16 square yards will be required; for 

 the fourth age 32 square yards; and for the fifth age 60 square yards. 

 The more space that is accorded to the worms in their first ages, the 

 more robust they will be; and if the space can be tripled instead of 

 doubled during the fourth age, and for the fifth age be 70, 80 or 90 

 instead of 60 square yards, the harvest of cocoons could be raised from 

 60 kilograms to 70, 80, or 90 kilograms per ounce of eggs, the quality 

 of silk also being superior. 



Temperature. 



The silkworm is not a tropical insect, and attains its best develop- 

 ment between the temperatures of 6$~ and 77° F. It is safe to adopt 

 the mean between these two temperatures for the general rearing. 

 Each cultivator, however, may suit his convenience, remembering that 

 to fall below or to exceed the mentioned limits of heat is detrimental 

 to the worm, and will affect the quantity and the quality of its spinning. 



From the second age the temperature should be from 70° to 1'2 D F. 

 and should be kept as uniform as possible to the end of the rearing. 

 The time which elapses between one change and the following one may 

 be much shortened b}^ raising the temperature and feeding oftener. 

 Such hasty rearings ma} T be made in twenty two to twent3 T -four da} T s. 

 They are, however, to be condemned, as contrary to the nature of the 

 silkworm. Meals following each other too closely can not be properly 

 digested, and are likely to cause disease. Besides, hasty rearings 

 require more labor, and the service must be kept up night and day. 

 As there is danger in too high a temperature, so there is danger in 

 one that is too low (64° to 68° F.). A rearing that is too prolonged, 

 lasting over thirty-two days, is to be avoided to escape the heat of 

 June, under which the beds are more likel} 7 to ferment, causing disease; 

 the worms have less appetite and leave more leaf from one meal to 

 another; the changes are slower and less likely to occur instantane- 

 ously; and there is more risk of muscardine or calcino, a disease due 

 to a mold. 



Both hasty and tardy rearings are, therefore, to be proscribed, and 

 those conducted in twenty-eight to thirtyy-two days alone are recom- 

 mended. This lapse of time permits the leaves of the mulberry to 

 acquire maturity, and the growth of the worm should be relative to 

 that of the leaf on which it feeds. 



