12 SILK CULTURE. 



most common at the 4th molt. These diseases need not become too 

 troublesome or serious if proper care and attention be given to the worms. 



VARIETIES OR RACES. 



The dififerent varieties of Silk Worm have been produced by domesti- 

 cation ; the different climates into which it has been carried having effected 

 changes in the habits of the worm, the shape and color of the cocoon, or the 

 quality of the silk. There are dififerent varieties of the silk worm. The 

 " Annual," which producess only one crop of silk in a year — the " Bivoltin" 

 or " 2-crop worm," of which this book treats, which, like the "Annual," 

 hatches in April or May ; and which unlike the Annual, again hatches for 

 a second crop in 8 to 12 days after the eggs are laid by the first brood. The 

 eggs of this second brood are always laid away for the next spring crop ; for 

 if hatched they would not live, there being no food for them so late in the 

 season, and the weather being unfit to rear them. " Trevoltins" produce 

 three annual broods. There are also " Quadrivoltins ;" and in Bengal a 

 species known as " Dacey" is said to produce 8 broods in the course of a 

 year. Some varieties molt only three times instead of four — especially in 

 warm countries — as also do the " Trivoltins." Varieties are also known by 

 the color of their cocoons, " greens, whites and yellows," and also by the 

 country in which they best flourish. The three most noted varieties are 

 " Italian," producing fine, small yellow cocoons. " French," producing 

 large yellow and straw-colored cocoons. "Turkish," producing large white 

 cocoons, and the "Japanese" white and green, and the "Chinese" white 

 cocoons. Some of these are " annuals," but the different colored cocoons 

 are generally called by the above names. The silk of the " white" cocoons 

 is the most valuable in commerce, but the "straw-colored" is most sought 

 after. The races producing the yellow and straw-colored cocoons are con- 

 sidered the most vigorous. 



WINTERING AND HATCHING. 



The importance of having the eggs free from disease and of good 

 races, has already been shown. They should be kept in tin boxes to pre- 

 vent the ravages of rats and mice, and be hung by string or wire from a 

 joist in cool, dry cellar where the temperature rarely sinks below the freez- 

 ing point. They should be occasionally examined to see if they are affected 

 by mold. If this should be discovered on them, it must be carefully rubbed 

 or brushed off them at once, and they should be put in a drier place. The 

 tin boxes may be perforated on two sides and the holes covered with fine 

 wire netting. The temperature should never be allowed to rise above 40°, 

 but may fall to freezing point without injury to the eggs. They should be 

 kept at this low temperature till hatching time, which will be when the 

 mulberry leaves are about one and a quarter inches in length (middle of 

 April to May ist) and great care must be taken as the warm weather in- 



