FOOD OF THE SILKWOKM. 11 



The laying-, consisting of 300 to YOO eggs, is generally completed in 

 three days, 70 to 80 per cent being deposited the first day, 20 to 80 per 

 cent the second day, and a few the third da3^ The mother moth 

 dies six to twelve days later, her death being usually preceded by that 

 of the male. Death occurs more or less speedily, according to the 

 robustness of the moth, the temperature, and the tranquillity in which 

 it has been left. 



Thus in about sixty-fiv^e days the silkworm has completed its cycle 

 of existence, its three periods ])eing thirty to forty days in a larval 

 state, fifteen to twenty days as a chrysalis, and eight to twenty days 

 as a moth or perfect insect. 



The rapid development of the silkworm and its marvelous transfor- 

 mations indicate extraordinary power and very active functions. Its 

 respiration is almost equal to that of the frog and of certain large 

 birds, which is equivalent to saying that it must be always surrounded 

 by plenty of pure air. 



THE FOOD OF THE SILKWORM. 



The leaf of the white mulberry '^ is the natural and the best food for 

 the silkworm. There are many varieties of the white mul])err3^ — some 

 much better adapted than others to commercial silk culture, and some 

 better suited to certain localities. 



The race, the size of the worms, the variety and age of the mulberrj^, 

 the nutritive quality of the leaf, the year, the season, and the climate 

 make the requisite quantity of leaf very variable. The following is 

 given as a basis of calculation, all circumstances being considered, and 

 the leaves not being cleaned: For the larvje hatched from 1 ounce of 

 eggs, during the first age, 11 pounds of leaves; during the second age, 

 26 to 33 pounds; during the third age, 88 to 145 pounds; during the 

 fourth age, 261 to 352 pounds; during the fifth age, 1,510 to 1,760 

 pounds; or about 2,200 pounds in all, of which one-half is consumed 

 in the last six or seven days of the fifth age. 



The age of the leaf ."hould be relative to that of the worm. Young 

 worms fed on old leaf, or old worms fed on young leaf, are apt to 

 become diseased, and even though they may not die, will scarcely 

 mount or will spin indifferently. A change of leaf, too, should, if pos- 

 sible, be avoided, or made gradually. Fresh leaf only should be used, 

 and never when wet with dew or heated, or before it has in a measure 

 acquired the temperature of the room in which the worms are being- 

 reared. It should be gathered early in the morning or in the evening 

 and should not be bruised or torn, nor should the baskets or aprons used 

 to carry it be the same which are used to remove litter. To avoid 

 fermentation the leaves must be spread out in a cellar or cool, dark- 



"For complete information regarding tlie mulberry, see Bulletin No. 34, Bureau of 

 Plant Industry, U. S. Department of Agriculture. 



