18 THE CULTUEE OF THE MULBEEEY SILKWOEM. 



Wise precaution liaviiig been taken to destro}^ germs of disease in 



the rearing room, the new-born worms ma}' 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 j^ards. For the third age 16 square yards will be required; for 

 the fourth age 32 square yards; and for the fifth age 60 square 3^ards. 

 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 ago 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 68^ 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 afl'oct the quantit}^ and the quality of its spinning. 



From the second age the temperature should be from 70^ to 72^ 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 by raising the temperature and feeding oftener. 

 Such hasty rearings may be made in twenty two to twenty-four days. 

 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 likel}^ to cause disease. Besides, hasty rearings 

 require more labor, and the service must be kept up night and da3\ 

 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 thirt3-two days, is to be avoided to escape the heat of 

 June, under which the beds are more likely 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 thirty-two days alone are recom- 

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

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

 that of the leaf on which it feeds. 



